Discworld/WMG

'Warning: There may be unmarked spoilers for the Discworld'' series below. You have been warned.'''

Books with their own WMG page (if it’s not on the list and you have a guess for a specific book, please add it there)


 * The Colour of Magic
 * Wyrd Sisters
 * Pyramids
 * Eric
 * Reaper Man
 * Small Gods
 * Men at Arms
 * Maskerade
 * Hogfather
 * Jingo
 * The Truth
 * Thief of Time
 * Night Watch
 * Monstrous Regiment
 * Going Postal
 * Thud!
 * Making Money
 * Unseen Academicals
 * The Wee Free Men
 * I Shall Wear Midnight
 * The Last Hero
 * Snuff

Characters/Ideas with their own WMG folder (for those characters/ plot points that inspire mass wild mass guessing.)

Vetinari is so Genre Savvy, he can recognize main characters
Vetinari, being the genre savvy fellow he is, knows about narrative casualty. Instead of just going along with it, or using it occasionally to his advantage (like Granny Weatherwax), Vetinari is actively seeking out what he deems to be 'main characters' and is manipulating them to either be on his side, or be afraid of him. At the least he is using them to further his own ends. Think about it: in Unseen Academicals, he mentions how he likes keeping track of people who are unusual. In The Truth, he's been shown to go around to aspiring new business owners (or at least ones whose wares/business endeavors are strange, new, and potentially dangerous). He makes sure Moist and William de Worde know he's got an eye on them, and it all comes out to Ankh Morpork's (and so, by extension, his) advantage.
 * In Guards, Guards, he seems dismissive of Vimes, and yet interested in Carrot. Perhaps, he was like Pratchett himself and assumed that Carrot was the main character at first, until the point when Vimes got tossed in the cell with him. That it when he realized that Vimes was the main character, and changed tack immediately.
 * Oh my God, this is possibly one of my favourite theories ever. How have I never thought of this? For me, it's becoming canon.

Vetinari is a Time Lord.
No one's been a Time Lord yet on this page. Also, it would explain Fat!Vetinari of the first couple books. It's far from usual for a human being to go from really fat (I haven't read any of the books where he's described as such, but one of the Discworld pages on This Wiki describes the Vetinari of the first couple books as outright obese) to gaunt. Perhaps the reason he's implied to have looked much the same as a teenager as he does now is that, like Romana, he has a pretty good degree of control over his regenerations. It would also explain why he's so freakishly clever. And why when he does drink... wine, he only gets a little chatty and is a little less than blindingly fast in completing a Crossword Puzzle, even though he doesn't often drink, and so would not have built up a tolerance, and, again, is quite gaunt. While it would be strange for a Time Lord to need a cane, as they have a low-key Healing Factor, he may have healed ages ago and just thinks it gives him extra gravitas. Perhaps he keeps assassiny things in it.
 * The main problem with the sword cane thing is that in Making Money he practically outright denies that he has one, and in The Truth, his preferred weapon is a sharp knife thing. Also Findthee Swing is described as having a swordstick which rattled.

Lord Vetinari is a perfectly ordinary human being.
Despite his cunning, his magnetism, the scalpel-sharp wit he employs and a dexterity to juggle virtually anything (cities included), Havelock Vetinari is quite simply a 100% mortal man. He lives simply and has no thoughts for himself; yet a corkscrew mind is required to keep the wayward clock of Ahnk-Morpork ticking. The FACT that he could be—and in all likelihood, is—a mundane person is potentially more frightening than the idea of his being a vampire, zombie, Death/Time hybrid or the like. Look at what he's accomplished WITHOUT those supernatural traits. Then smile politely and back away slowly...
 * Ooh, Look at you. you're so sharp you'll cut yourself.
 * I don't think "ordinary" is the word you're looking for. Mortal, certainly, but given his accomplishments and skills, he is, by definition, neither mundane nor ordinary.
 * Vetinari is however quite happy to allow people to believe he is a vampire as he recognizes that if someone not understanding how vital he is to the city comes after him it is after all better they do so with seasoning and religious symbols than with say a sharp knife.
 * Do you mean that he is like Carrot's sword?

Vetinari is extremely Knurd.
Knurd is a concept mentioned in several of Terry Pratchett's earlier Discworld books, and is defined as the opposite of being drunk: All of your comforting illusions about the world are stripped away, and you see the world as it really is. Vimes is mentioned by Sergeant Colon as suffering from this condition, requiring about two pints to get back up to the human norm, and this is used to explain his extreme cynicism. It is also defined as being an incredibly unpleasant experience.

Vetinari seems to fit the qualifications for Knurd quite well; He is incredibly cynical about humanity, and the world in general. His expectations about the world are also generally fulfilled. Vetinari is nigh-impossible to surprise, and there is only one example that comes to mind when he was even mildly surprised, when the Night Watch at the end of Guards! Guards! only asked for a small bonus, a new kettle and a dartboard. Therefore, it seems that Vetinari's view of the world is quite accurate, fitting in with the 'sees the world as it really is' aspect of Knurd (although his exceptional predictive abilities would probably also come from his network of spies, and his brilliant mind). Additional evidence is found in Unseen Academicals, where Vetinari, after consuming enough alcohol to make some Ankh-Morporkian football team captains (Tough even by the standards of Ankh-Morpork) pass out, does not in fact appear even mildly drunk that day or the next, other than finding the crossword slightly more difficult, but does act in a slightly more normal and human manner. Of course, given the amount of alcohol he consumed, he would have to be incredibly knurd not to have reached drunkenness, certainly far more knurd than Samuel Vimes, who was quite capable of becoming drunk after a few drinks.

This also provides an explanation for his attempts to improve the city; Since he sees the world as it really is unless he consumes massive amounts of alcohol, he can either attempt to consume enough alcohol to bring himself back to the normal level of drunkenness, or try to make the world a better place, so that seeing it as it really is becomes less unpleasant. Given the amount of (apparently incredibly strong) beer he consumed without becoming drunk, the amount of alcohol he would have to consume to bring him to sobriety would probably kill him long before it cured his knurdness. Therefore, Vetinari set out to improve the world, and started in Ankh-Morpork, arguably the most unpleasant city on the Disc (as well as the city where he holds a decisive advantage, having been trained here as an assassin, and doubtless possessing many connections with fellow Assassin's Guild-trained noblemen.)
 * He was, however, very surprised that A.E. Pessimal attacked a troll with his teeth. Gobsmacked, even.
 * His surprise could have been faked. After all, Vimes needed someone to do the paperwork, but would probably not react well to yet another person being forced into his department by Vetinari, particularly when he had just been forced to accept a vampire into the Watch.
 * He was also surprised by the New Firm's ambush, proven by the fact that Mr. Pin and Mr. Tulip not only survived the encounter, but successfully knocked him out. Sure, you could argue that he let them win, but that would require Vetinari to voluntarily place himself at the mercy of an enemy's hired muscle, gambling his life on said enemy's wish to keep him alive, and the New Firm's professionalism in complying with that wish. Given that half of the New Firm regularly snorted borax cut with talcum powder, those are pretty long odds for a bet...
 * He's knurd, not omniscient. Being knurd seems to sharpen one's senses, and make one better at using them. This (combined with his vast information-gathering network) might make him seem omniscient at times, but in the end, there's still a limit to what he can see.

Vetinari is grooming Vimes to be Patrician.
Think about it. He knew Vimes when the latter was just a drunk. He was able to recognize that here was someone honest, capable, and fairly devoted to the city. As the series progresses, he's gradually raised Vimes from Watch Captain, to Watch Commander and Knight, to Duke. He's sent him abroad twice to act as Ankh-Morpork's representative, despite the fact that Vimes is in no way connected to the diplomatic corps. All done to make Vimes not only capable of ruling the city but acceptable to the various power groups- they all know he's trustworthy and fair even if they don't like him. So why has he been doing all this? Carrot. Vetinari recognized early on that Carrot believed in Vimes and would obey his orders completely. If Vetinari were to die without a designated successor, either Carrot would be made king by popular acclaim, or the guilds would appoint a puppet ruler- causing so much corruption that Carrot would stage a coup. Either way, the city becomes a monarchy, and eventually stagnates. BUT if Vimes is Patrician, Carrot won't act against him. Moreover, if Vimes asks Carrot to assume the role of Patrician but not King- effectively asks him to renounce his claim to the throne while assuming leadership of the city- Carrot would do it. Since (as far as we know) the Patricianship is not a hereditary title, there's no risk of an unworthy heir taking the throne- especially since Carrot would probably run the same gambit to find his own successor. Vimes is the ONLY one who could convince/order Carrot to do this.
 * VASTLY more likely that Vetinari is grooming Moist von Lipwig to be the next patrician, and expecting Carrot to replace Vimes.
 * This troper disagrees. Moist von Lipwig's skill lies in manipulating the common man and, while most of the power in Ankh-Morpork lies in the guilds, rich, or titled, they will see Moist as an upstart rabble-rouser (see Reacher Gilt and the Lavishes). And Moist lacks the killer instinct Vetinari has for keeping people like that in line.
 * The nobility doesn't elect the Patrician, the Guild leaders do. Granted, there's some overlap, but Vetinari has allowed so many common-class professions to form their own Guilds that the aristocratic ones are bound to find themselves heavily outnumbered next time the issue arises.
 * Moist however, is very good at being popular.
 * Vimes is a policeman, and will stay a policeman. The position of Patrician is vastly different from a policeman. A policeman is a policeman. Having a Patrician be a policeman won't work. And Vimes isn't very popular. Vimes doesn't have the mind to manipulate people to do what he wants him to do (like Vetinari) nor does he have the charisma to get everyone to like him (like Carrot or Moist Von Lipwig) and he isn't the type of person who can make everything run greatly (like Lipwig). It may be true Lipwig can't keep everybody in line through careful manipulation, but Vimes can't do it either. And Lipwig actually can get most everybody to run with him. Carrot could do it too, but it seems like both Vetinari and Carrot don't want Carrot to be leading, otherwise Kings will come back. Vetinari probably sees that. If Vimes was Patrician, he'd probably arrest different countries, but the city would be a mess. Which is why, actually Vimes being promoted to Duke makes sense.
 * Give or take a few years, Vimes and Vetinari are the same age. Plus, Vetinari is a genius whose foiled assassination attempts are at the very least in triple figures, and Vimes seems to enjoy attacking trolls, chasing criminals over rooftops, and having at least three near-death experiences per book. Why would Vetinari groom a successor who will probably be dead before he is? It makes no sense. Moist von Lipwig is MUCH more likely, by reason of age, skills, and personality.

Vetinari is a male witch.
It's been made quite clear that witches and wizards are gender-bound only by convention, not a biological imperative. Vetinari had the perfect qualifications to being a witch apart from his gender and birth. Consider how similar his way of leading Ankh-Morpork is to the way Granny Weatherwax runs Lancre, and how he knows so many tricks that are like magic unless you know how they are done (which doesn't make them any less magical). Like Granny Aching, Vetinari would never acknowledge the title of a witch, but fulfills every qualification in the book. He may even have talent for genuine magic, but like all good witches, refrains from ever using it.
 * It's true that he does use headology on people. And I remember instances where he intimidates people by being very polite, like the way Granny Weatherwax also intimidates people. But when he was a boy, he was being trained as an Assassin, not a witch, as we know from Night Watch. From the history we know of him, where does witching fit in?
 * Granny Aching never got any official witch-training either, and never did anything exactly magical, but there's no doubt that she still was a witch in every way it counts.
 * He does do a little magic. He "borrows" the perceptions of rats, scorpions, and snakes (as seen in Men At Arms); and communicates with them. This is by large his spy network; he just employs enough human ones for credibility.
 * That wasn't Borrowing, that was negotiation. The rats in his dungeon were probably related to the Clan from Amazing Maurice, and the spiders and scorpions (who'd been winning out over the rats before he intervened) had presumably eaten enough of them to gain intelligence as well.

Lord Vetinari has a very slow metabolism
He survives on bread and water. Literally. This also explains his slightly changed behavior in Unseen Academicals, he was slightly drunk throughout. The alcohol takes a while to go through, but also takes a while to be absorbed, so is taken in slowly. The laughter and the more-obvious-than-one-would-expect possibly-flirting with Lady Margolotta was Vetinari drunk. Naturally, he is calm and logical, but that's sort of like saying Batman is still using plans. Even if he gets knocked out, that's true.
 * He was also somewhat overweight in the beginning of the series.
 * Maybe in the beginning he was overweight, then became extremely busy and survives on water, and thinned down because he ate so little.

Vetinari is grooming Moist von Lipwig for the Patricianship.
Everybody dies eventually, and when Vetinari's time does come, who better to take over than the Flying Postman, the Man In The Golden Suit, who's done more by winging it than many men have done through careful planning?
 * Possibly, this is only because his attempts to groom Captain Carrot for the office failed. Carrot would be perfect for the job, being incorruptible, simple but with a powerful mind, and absolutely dedicated to the city. Unfortunately, he feels he can do more as a policeman than as a ruler, and is also afraid that if he became ruler, it might lead to.
 * Alternatively, it could be very well be the reverse; the Patrician and Carrot know they're fighting Narrative Causality, which will be trying to push Carrot into, hence why finding a good replacement for the Patrician is a priority. Carrot would almost certainly not make a good Patrician --.
 * Alternatively, Vetinari just getting things ready for Carrot; he's the only person Vetinari knows he doesn't have to manipulate. They both have an "understanding" of how the city needs to work. Carrot may have the ability to step into the position of Patrician easily, but with a properly trained Vimes and Von Lipwig at his disposal, he'd be able to keep the position.
 * Drumknott may also be getting a position; Vetinari is clearly training him, at the least to be the perfect clerk.
 * Except Drumknott would seem to have been born a perfect clerk. If anything, Vetinari's been training him to become at least an amateur human being.
 * More likely Drumknott will have a secured position as the next patrician's secretary, having invaluable access to dossiers and tabs on secrets and plots, but not the brain or charisma to run the city himself.
 * Unlikely. Drumknott role in Narrative Causality is to play The Watson to Vetinari's Holmes.
 * Vimes is a more obvious choice for Patrician, but consider. They're pretty much the same age, and Vimes works at a hazardous occupation and is a recovering alcoholic, ie. not all that healthy. Vetinari might outlive him, to be honest. As well, Vimes is a very angry guy without a great deal of political tact. He offends everyone. That's his purpose in life. In short, he'd make a terrible Patrician, but incredible Assistant Patrician.
 * Or maybe all along Vetinari has been training Vimes to be an incredible Commander of the City Watch.
 * Yet another possibility: Vetinari would never be so short sighted as to groom a person as a replacement. He is grooming several people as replacements.
 * Naturally. This is the man who named Vetinari Job Security. Lipwig, Vimes, et al. are part of his work to avert the inevitable when the indespensible leader dies.
 * Moist Von Lipwig has been shown to be a character who doesn't do well over long periods of time; this leads to a few options if we're still going with this idea. One, Vetinari knows that he doesn't do well over long periods of time, and thus keeps giving him new responsibilities to keep him entertained and to try to push his attention span a bit longer so that one day he will be equipped to run Ankh-Morpork. Alternatively, Vetinari knows he's a short-term type of guy, so has him in reserve as a potential temporary Patrician, should anything like the events of Feet Of Clay repeat themselves.
 * Moist could do well long-term if the job was dangerous and/or exciting enough; It's just that he manages to make things work so well they become boring to him. And Vetinari mentions that the politics of the city are so poisonous and controlling the Guilds so difficult that by comparison, nothing seems hard, indicating Moist would never run out of problems that needed solving, so he'd be a good long-term choice, despite his tendency to boredom.
 * A tendency that may decrease in time, once Moist marries Adora Belle and has a family to feel responsible for. He's also only in his mid-twenties, so can be expected to outgrow the worst of his thrill-seeking habit by the time Vetinari retires.
 * A further possibility: the actual function of the Lord Vetinari Ward from the end of Making Money is to produce the perfect replacement for Vetinari—that is, a perfect copy of Vetinari. This is the real purpose behind the eyebrow-raising competition—it's actually a Secret Test Of Vetinariness.
 * This has already happened
 * The fat guy from The Colour of Magic was the original. The Magnificent Bastard from the later books is a copy.
 * Or, maybe he's grooming a council to take over for him. None of the people mentioned can fill Vetinari's shoes. But together, Moist, Vimes, Carrot, Drumknott, and possibly one or two others could.
 * Another alternative, of course, is that Moist is just a convenient distraction. Vetinari doesn't intend to ever give up the Patricianship; see below.
 * Even if he really does intend to be permanently permanent, it's to his advantage to have one or more proteges in the wings. Why? Because it's a discouragement to all those pesky troublemakers, foreign or domestic, who keep trying to depose him. If Vimes and/or von Lipwig are just going to keep the city running exactly like Vetinari set it up to operate, even in their boss's absence, then booting out the Patrician won't profit his political enemies much, if at all.
 * How about not Moist, but... dun dun dun... Adora Belle Dearheart!
 * This might make a weird kind of sense - they both have the same unapproachable no-nonsense personalities, unswerving dedication to their cause, and over the course Vetinari's rule from Feet of Clay to Making Money, we've gone from human women having only the career choice of someone's wife, maid, or whore to mentions of being involved in the plans for the Undertaking, in the Dark Clerks, etc...

Vetinari is a vampire who has replaced bloodlust with devotion to politics.
Lady Margalotta turned him during his great sneer.
 * Problem: Vetinari walks around in the sunlight without a hat. While vampires can operate quite decently during the day, they need to wear hats or veils to ensure no strong enough sunlight hits them.
 * Solution: Vetinari is a man of unbreakable will and could have trained himself the same way Count de Magpyr from Carpe Jugulum did. This is also why he can appear in the pictures in the Ankh-Morpork Times, despite the vampire photographer dissolving into dust each time he takes one.
 * Problem: Vetinari visited Uberwald as a young man, and is now clearly much older. Vampires do not age.
 * Solution: Neither does Vetinari. He merely uses cosmetics and good acting ability to appear older. His use of a cane is fake; he just started carrying it after being shot because people would expect such a serious wound to have long term effect. He also started the rumor going around that he dyes his hair. Why bother actually dying it gray to look old, when he can start the rumor that it is gray and he simply dyes it black. If only there were some precedent to vampires being vulnerable to arsenic...
 * Problem: Angua doesn't appear to sense any such thing about him.
 * Another problem: We see him shaving in Guards! Guards!, and he uses a mirror to do so.

Vetinari is a latent vampire.
Think about it Vetinari definitely has vampiric traits (which would explain the popularity of the above theory-to the point where the author included it in one of the books as an in joke) but it's a theory that's been almost completely Jossed, which is where the latent vampirism comes in. (apologies for the slightly sloppy layout, I'll be back to clean it up later)
 * Lady Margolotta bit him on the grand sneer however she didn't complete the process for some reason (maybe it was an accident? I'm not sure, still working on this thing) leaving him with some vampire traits; a lack of a normal need for food, sleep, etc., incredibly pale skin and very sharp reflexes (for someone pushing 50) but not making him a true vampire.
 * Mind you, when he actually dies who knows....
 * So he's a Blood Bond?
 * A very Discworld theory: By looking and acting so much like a vampire, and having so many people believe he's one, he'll become a vampire on his own.

Vetinari will become a zombie.
Sure, he has to die sometime, but nobody says he has to pass on. Like the books say: it may cost a million dollars to kill Vetinari, but it'll cost much more to make him stay dead.
 * Alternatively, as a variation on the above theory, Vetinari is not a vampire yet (could he have been poisoned and injured by the gonne if he were?), but he is friends (and quite possibly more) with one. He will arrange to be turned near the end of his life.
 * Note also that Vetinari wishes to be cremated when he dies; this seems like it would prevent any form of undeath, but if anyone could not only find a way around this but use it to his advantage, it's Vetinari.
 * This would be similar to the way the "angels" offer worked for Moist (and Owlswick in Making Money). "Lord Vetinari certainly is dead, we have his ashes right here. The new Patrician is completely different."
 * Probably if this happens, he'll pass on, be cremated, face Death, look at Ankh Morpork and refuse to die because he thinks that the city is not yet ready for his departure, nor is his successor ready to step in. Then he'll turn around and go back to life. Maybe while they're about to cremate him.

Vetinari isn't grooming the city's next Patrician, but is grooming the city itself to carry on his work.
Think about it. Even if he did hand-pick the next Patrician, he'd have little influence on the office after that. Undeath is an option, but it's not perfect, since there's still ways to get rid of a zombie or vampire, and having a power behind the throne would itself negatively affect the city. And after that, who knows when the next Mad Lord Snapcase will rise to power? So instead of working on one piece, he's working on reshaping the board; the rise of the Guilds, the changes in the Watch, and the re-opening of the Post Office are just a few of the ways he's changed the city itself, and a new Patrician would be hard-pressed to reverse Vetinari's progress. His successor is his life's work; the new Ankh-Morpork.
 * Note that Vetinari now has a Device which can power every machine in the city. Perhaps he's literally granting it a life and will of its own; Hex could become the City's mind, and the Device its heart.
 * The logical end of this line of thought is that Ankh-Morpork will become a Magitek Transformer.
 * Another possibility: A city is a thing of bricks and masonry. A city has libraries, journals, rooms filled with laws, theologies and poetry laid out in text, and we know what the right words in a clay shell can do on Discworld...
 * And the series has some clues toward this possibility. Reaper Man introduced the concept of city predators, and lines like "So we have the cities -- big, sedentary creatures, growing from one spot and hardly moving at all for thousands of years. They breed by sending out people to colonize new land. They themselves just lie there. They're alive, but only in the same way a jellyfish is alive."
 * The 'footballs' in Unseen Academicals are a variation of the 'shopping cart' eggs seen in Reaper Man.


 * Another possibility is that, when Vetinari dies, people will keep pretending he exists because they can no longer take care of themselves. It'll be sort of like how Big Brother is a reassuring incarnation of authority, only (hopefully) less Dystopian.


 * This WMG would explain the theories that 'Vetinari is grooming X as a next Patrician'. He actually doesn't intend any specific person to rule, he is creating a network of services run by people with unusual talents that keep the city in check.

Vetinari didn't quite deserve his reputation until after the events of Men at Arms.
See its WMG page for the hypothesis.

Vetinari is going to be Death's new bookkeeper/assistant.
Think about it. Albert is very close to dying for real, and doesn't it seem so fitting for Vetinari? Admittedly, it wouldn't have the hilarious clash of personalities that Albert and Death have...
 * Actually, another possibility is that Drumknott will be Death's new bookkeeper/assistant. He is an impeccable clerk. Vetinari might nominate him for the job. Like in that fic.

Vetinari and Lord Downey conspired together in murdering Vetinari's predecessor.
I don't think it's stated outright, but I'd probably assume Vetinari killed his predecessor, and I would bet that he had Downey's help doing it. The two were enemies in youth, but by the time of the books are reluctant allies. In Night Watch, Vetinari killed one insane patrician when he was a lot younger, so he probably killed the other later. As shown in Hogfather, Downey falls into Even Evil Has Standards, and so it's not out of the question that he would assassinate someone who really deserved it. IIRC, the previous patrician was the guy who was hung by his figgin (a pastry). Perhaps Downey poisoned his figgin and afterward, he and Vetinari took out any remaining supporters of the guy.

Vetinari can detect auras and use them to know the emotions of people around him.
Vetinari has been able to do some strange things that can always be explained by him just feeling the emotional atmosphere of a room. He can tell when Moist von Lipwig is about to try to cough to announce his presence without looking at him. He knows exactly how long to stare at several characters for just long enough to make them uncomfortable, and then for 5 seconds after that. Plus, it just seems like something he could reasonably do, or at least a less mystical version of the same ability.

Vetinari banned mimes from Ankh-Morpork because he knows they're really the Fools' Guild's elite hitmen.
The so-called Fools' Guild is actually a massive spy network, to which Guild-trained jesters feed all sorts of valuable and/or scandalous information on their influential employers. Any spy network that extensive is going to need a few professional killers (not Assassins, different Guild) on staff, to covertly silence anyone who might betray its existence or circumvent its plans. Clowns or jesters are conspicuous by definition, but mimes are specially trained in skills like acrobatics, soundless movement, and holding perfectly still (a favorite tactic of Vetinari's, when he was trained in assassination!). They don't speak and wear makeup that makes them anonymous; if a mime attacks you, and you survive, you won't be able to identify them by voice or looks. And they tend to wear lots of black, like "official" Assassins do ... except mimes can substitute dark gray without getting chewed out for it, making them far stealthier than Vetinari's old classmates.

Terry Pratchett has hinted that Vetinari prohibited street theater because he knows something. Knowing that mimes are killers for their Guild, who don't make his fellow Assassins' usual mistakes, might just be it.

Vetinari will become the God of Ankh-Morpork
Like the zombie theory, but on a bigger scale. Vetinari will become the patron deity of Ankh-Morpork after his passing, and continue to guide the city for the rest of eternity. While simultaneously manipulating the other gods into making him their leader. That's right, Vetinari will become the de facto ruler of the world.

If Pratchett ever knowingly writes his last Discworld book, Vetinari will die
Vetinari is widely accepted by, if not most, at least a large number of fans as the series most awesome character. He appeared (possibly, or maybe an alternate version of him, or maybe just not him at all, but never mind) in the first book, becomes the series' reigning Magnificent Bastard, and will cause a fairly massive outcry if Pratchett ever kills him off. There are quite a few succession theories, but Ankh-Morpork without Vetinari might be quite difficult to write about, as well. If Vetinari dies, it might be the right time for the Discworld to die with him.
 * Or, as a similarly-climactic finale, the last Discworld book could be written with Vetinari as the protagonist. The series' penultimate social magician, finally revealing the secrets of his Magnificent Bastardry for all to see!
 * Jossed - it was who died in the final Discworld book.

Vetinari is the rightful heir to the throne of Ankh-Morpork
1. He's a member of the aristocracy. 2. We know little about his origins other than having an aunt. And even she is shown to have come from a mysterious other city - mention is made of Genua or Pseudopolis, but we never see what. There's also no mention of the Vetinaris having an Ankh-Morpork family home, the way the Ramkins or Selachiis do. 3. He's well tuned to the public need. 4. Everything he does is to the betterment of the city. 5. Both he and Carrot are repeatedly mentioned as having fathomless blue eyes...and there's a rumour going round that Vetinari dyes his hair. The reader assumes it's from grey to black, but what if it were red?
 * It follows that he's Carrot's long lost brother, who was at school in the Assasin's Guild when Mom, Dad, and Little Brother went on the fated carriage ride. They're so different because they embody different narrative roles and archetypes. (And if Vimes ever found out, he'd go *spare*.

Vetinari is an Orc, or at least part Orc
In Unseen Academicals Vetinari is very interested in the Orcs as a whole and, like Orcs, it has been shown he has a photographic memory, a quick mind and can pick up abilities almost immediately.

Alison Weatherwax is still alive.
Granny Weatherwax has a grandmother, the legendary Alison Weatherwax. Some say she went bad, others (Granny for one, anyone within earshot of her for another) say she didn't. She left Lancre long ago, but so far we have no proof she died. We do know she killed Bela de Magpyr about 50 years ago, and would be 125 if alive today. This is not especially impossible on the Disc.
 * The Discworld Companion as good as confirms this; long before Alison was mentioned in Carpe Jugulum, she had an entry commenting that Lancre's registar's office had no record of her death.
 * Of course, The Lancre registrar's office is basically just Shawn Ogg. He may have been busy being the highway department or commissioner of fish and wildlife that day.
 * This may or may not have anything to do with the clock Granny is so particular to keep wound in Lords & Ladies. (If it does, it can't be as simple as "Alison dies when the clock runs out", because that's already happened, and Granny just wound it up again as soon as she had the chance.)
 * Note the similarity to the witch from Wintersmith whom everyone thinks has a rewindable clock instead of a heart.
 * Quite possibly then it is everyone perceptions that alison is kept on the right side of the veil by the clock which is keeping her alive. Granny of course wouldn’t be fazed by this, so it doesn’t matter if she has the clock wound up so long as no one else notices its run out.
 * Or maybe she is Lady Margolotta...
 * and your reasoning for that is? (I’m not complaining about the rather random theory, I’d just like to know how you got to it.)

There are male witches.
Just as "there are no female wizards", enter Esk and the Wizards of Krull, "there are no male witches". But there are several people who have been referred to being people who are as close to be witches as possible whilst in trousers, such as Mr. Brooks and Jason Ogg. After all, 99% of magic is knowing one extra fact. Insulting Mr. Brooks (the Royal Beekeeper) is almost as dangerous as insulting a witch. Jason and Brooks both reacted in the "correct" way to elves, and seemed resistant to glamour; Jason even got warnings about the incursion. Even Granny herself considers witchcraft less about wearing pointy hats and doing magic, and more about a point of view. She considers Mrs Palm to be a "practically a witch" even though acts of negotiable affection would definitely not constitute witchcraft. The simple fact is that it is possible to be a witch whilst not being aware of that fact, so why not do that and be male?
 * According to Granny, there are enchantresses (female wizards) and warlocks (male witches), but these don't really count somehow. Perhaps they have the innate abilities Wizards and Witches have, but lack the proper narrative push education/etc to use these abilities.
 * Or perhaps Granny is just a perpetrator of good old-fashioned sexism. Or, even more likely, of good old-fashioned narcissism: Them other girl wizards weren't taught by a Weatherwax, were they?
 * Maybe Granny Weatherwax is just wrong.
 * Bite your tongue!
 * Who dresses in black, always seems to be thinking about six steps ahead of everyone else on average, makes knowing all the facts his job, and is dangerously Genre Savvy, and as iron-willed as Granny herself? Vetinari, of course.
 * ...I think I have a new OTCrack Pairing...
 * Walter Plinge  is another candidate for latent male witch. Who else but a witch could make dead rose stems bloom in the darkness, or  ? Witches are attracted to masks and stages, and Walter could've been an excellent witch if he hadn't opted to specialize in music instead.

Granny Weatherwax and Tiffany Aching became witches for similar reasons
In The Wee Free Men, Tiffany relates the story of Mrs. Snapperly, an old woman who was cast out of her home and eventually died because people thought she was a witch. Tiffany's response: Become a witch herself to make sure no one dares try that again. When asked by Nanny Ogg why she got into witchcraft in The Sea and the Little Fishes Granny Weatherwax responds with "I dunno... even I suppose." In her youth, Granny witnessed a similar incident. Not identical, given Lancre's respect for witches, but same in the essentials, an act of cruel stupidity that someone with respect could have prevented. Thus, she sought out the most respected position she could think of: Witch.

Granny Weatherwax gained some of Lily's power when she escaped from the mirror.
This would explain the rapid increase in power in books following the mirror scene in Witches Abroad. Notice how much more evident examples of non-headological magical prowess are demonstrated after the second "inside the mirror" scene. There's the business with The Swarm in Lords and Ladies and the "Weatherwaxing" of the Magpyrs in Carpe Jugulum. There are some signs, even, in Witches Abroad. For starters: there was only one Weatherwax found after the business with the mirrors, Granny finally takes a look in a mirror later on, and she manages to work the wand despite having no actual experience with it. One Weatherwax has already been shown to be quite powerful, and we've seen in Wyrd Sisters what three witches can do together. Imagine what one Weatherwax with the power of two could pull off.
 * In Equal Rites, Granny is perfectly able to duel the Archchancellor of Unseen University to a standstill, and that was back when they were really enthusiastic about Klingon Promotion. She was always that powerful, probably even more powerful than Lily, she just knows the consequences of using power too well.
 * Additionally, Equal Rites showed that magically speaking, wizards are the mighty glaciers while witches are fragile speedsters. Granny's mastery of headology and all-around sneakiness means she has transcended that and become the magical equivalent to a Ninja.

Greebo was originally a human that got turned into a kitten.
The human-ifying didn't tell him "Yer a human! Be human!" It just made his shape remember, "Oh, yeah, I'm a human..." only he had gotten used to his cat form over the last twenty years. His human side was keeping him alive and in shape (heh) for however long it was between the end of an unusually long-lived cat's lifespan (or at least end-of-prime) and at least the events of Wintersmith. He probably got convinced into being a cat after being lecherously rude in the presence of, or towards, a witch, and decided he liked being a cat (once he aged up a bit from being a kitten, anyway) because he could fight/eat/have sex with pretty much anything, since he was a cat and not a human any more.
 * Impossible, I'm afraid. Greebo's eye is that of a cat, therefore he must have been born a cat; it is utterly impossible, even for the gods themselves, to change the manner or nature of a being's eyes. This is why the Duc had to wear sunglasses.

Greebo's a fiend from hell.
Nanny Ogg says so in Witches Abroad. (This troper thinks she was speaking metaphorically, admitting for once that he wasn't still the cute little kitten she treated him as, but the theory appears to have been lost sometime in the past six months and it may as well be replaced.)
 * Except Lancre hasn't been overrun with fiend-spawned cats, despite most of them being Greebo's offspring. Granted, there was that two-headed kitten, but that's just genetics.

Granny Weatherwax is the preincarnation/reincarnation of Sam Vimes. Or vice versa.
They are, after all, basically the same person. Both of them are inclined towards badness and force themselves towards good. They both see the world as it really is, rather than how it's expected to be. Their respective mottos: "I can't be having with this," and "Not in my godsdamned city," express a more or less identical sentiment. They're both rather cautious about using magic. Both of them have a rather more optimistic counterpart/subordinate who's also just a bit better at what they do: Word of God says that Nanny Ogg is more powerful than Granny, but she has the good sense to keep it to herself, and Carrot is, in essence, singularly responsible for the modern Watch. There are a few differences, of course; Vimes isn't nearly as concerned with being right or winning as Granny is, and Granny doesn't have the same respect for the Rule of Law that Vimes does. But reincarnations don't have to be identical.
 * Wait a minute, Nanny is more powerful than Granny? Could you provide a link to that, as it doesn't make sense. If Nanny was more powerful, then why was she not able to defeat Lily in Witches Abroad, or resist the Elves' Glamour in Lords and Ladies?
 * The quote, from Terry Pratchett, in The Art of Discworld: "I've always suspected that Nanny is, deep down, the most powerful of the witches and part of her charm lies in the way she prevents people from finding this out." Granny has to defeat Lily and the elves because she's basically willpower incarnate, much like Vimes. Nanny may be more powerful, but Granny is stronger. Vimes, once again, is not quite as good a copper as Carrot, who knows everyone and is unfailingly polite and assumes the best of everyone. But at the end of the day, Carrot respects the law because it's The Law and he's a dwarf, while Vimes respects the law because Godsdammit, Someone Has To. It may not make him a better cop, but it makes him better. More just. Whatever. Getting distracted. Point is, yes, Nanny's the powerhouse of the group.
 * Hmm, like diamond versus tempered steel? Interesting. (I'm not sure if the analogy holds unless you view it in reverse, though, since diamond's schtick is being unbendable yet brittle, and steel has just a bit of give at its most durable.)
 * If you're looking for a canonical version of this theory, it shows up in I Shall Wear Midnight. Sure, it's just a rumor, but Tiffany can believe it.
 * The biggest problem with this WMG is pride. Granny's, you can bounce rocks off. Vimes's is just barely enough to keep his badge from getting grimy.
 * Vimes takes pride in the fact that he isn't proud. He's surrounded on all sides by his so-called betters, who universally deride trolls and dwarfs and people from Howondaland, but Vimes doesn't really think he's better than anyone else, which makes him better than the peerage. It's "practically Zen."
 * Darktan might be another reincarnation of the same character.

Princess Esme is going to be a really powerful witch.
Spelling is her middle name after all. (Literally.)

If Pratchett ever knowingly writes his last Discworld book, it will be a witch book
The witch books seem to be the ones most concerned with endings, and the end of an era and passing of the torch in particular.
 * Confirmed.

Granny Aching ate'nt dead.
Like her "little jiggit", she taught herself Borrowing, intuitively using this talent to commune with the sheep and her dogs. When she sensed her approaching death, as all witches do, she stretched this gift to its limit, and achieved a feat roughly on par with Granny Weatherwax's bee-swarm control: she Borrowed the slow, sleepy, collective mind of the Land Under Wave, the Chalk itself, leaving her failing body behind. She's still there, a part of the land she loves, watching over Tiffany and occasionally helping her.

Granny Weatherwax isn't a female alternate of Vimes, she's a female alternate Sherlock Holmes
They're both proud, unsociable, highly talented Good Is Not Nice Guile Heroes who are thin and wiry, have intense pale eyes, and are interested in beekeeping. The major difference is that, apart from being rural and female, Esme Weatherwax is in an occupation that requires a certain amount of common sense and a broader skill set, and she's not in a position that allows for any self-destructive habits.

Nobby Nobbs is immortal.
Think of it. Back in Hogfather, Death himself had no idea what or who Nobby was. Up until then the only person Death hasn't been sure about was Rincewind. Nobby needs to carry a signed paper around saying he's human, but the only ones who can honestly give testament to that are his 'mother' and a midwife. And we all know how odd things can happen at births on the disc. ..
 * But does Death necessarily know everything about a person on sight? He needs to know when someone will die, yes, but not necessarily much about their lives prior to that. Plus, if he were omniscient, he wouldn't need to consult reference books about things like the dangerous animals of Fourecks.
 * The fact that Death saw enough of Nobby to not recognise him means that he's mortal. Actual immortals, like Lobsang Ludd, are invisible to him.
 * Death can see immortals just fine, actually; he sees Azrael in Reaper Man, and the Big A is as eternal an entity as any in the series. He didn't see Lobsang in Thief of Time because.

Sybil likes Nobby because she subconsciously recognizes him as the Earl of Ankh
One of Sibyl's flaws is thinking that Nobby's behavior makes him a lovable rogue instead of - well - Nobby. Blood calls to blood and they both belong respectively to the two oldest families in the city.

The answer of the equation Detritus almost solved was 42.
Because really, what else could it be?
 * I always thought that '=' just was the answer. When you solve an equation, as Detritus was doing, you basically simplify it by getting less and less numbers, in order to solve it. So if you got rid of all the numbers, you'd end up with a perfect equation, and that would be a good candidate for a Theory of Everything...if that makes sense. I think it does on the Discworld, anyway.

Captain Carrot is an incarnation of Stranger in A Strange Land's Valentine Michael Smith.
Both are amazingly kind, competent, simple humans who were raised by non-humans. Both teach their older, culturally-human mentors about humanity. And it's implied in Stranger that Mike's bodily form is just one of the incarnations of the Archangel Michael, who goes on "assignment" from time to time.

Captain Carrot is only so noble and handsome because the people of Ankh-Morpork believe that's what the kings of Ankh were

 * As evidence, in Feet of Clay, showing what a real lost noble would be like, after so many years of 'Good breeding'.
 * But, due to the belief that the kings of Ankh were so good and pure, it means that Carrot would never take the throne while Vetinari rules, because the people believe that the kings of Ankh only did what was best for the city, and Carrot believes that that's Vetinari.
 * The only sticking point I can see with it, is the fact that, if Carrot is all this because of belief, then why isn't his sword magical?
 * It is. It's not the kind of magical sword that goes 'ting' when the light hits it, which is what everyone expects at first a king's sword to do, it's what everyone, deep down, knows a king's sword really needs to be. Very very sharp, despite being left in a burned out wagon and stored in a box without maintenance for 16 years.
 * His sword is explicitly non-magical. Which leaves the other option, it's extraordinarily real, much like Death. Belief is what makes Death what he is and belief in Carrot (or Carrot's belief in his sword) make it exactly what it is.
 * That's the unusual thing about the sword - pretty much everything on the disc is magical, or at least partially, whereas Carrot's sword is very real. The more magic in something, the less real it becomes, hence what makes Carrot's sword very, very good at cutting things
 * Don't confuse Narrative Causality with Clap Your Hands If You Believe. Aside from a few specific cases (e.g. gods or the afterlife), Discworld does not do what people expect, it does what the narrative demands. Practically everyone believed the Disc was going to be destroyed by the Red Star in The Light Fantastic, yet the story had other plans. Carrot is the way he is because the story demands a worthy king, not because Ankh-Morporkians (a cynical bunch) ever actually expect to find one.

Vimes is on track to become the God of Watchmen
As mentioned above, the nature of belief in Discworld affects the object of the belief. We have any number of examples, from Om to the Hogfather, but most pertinently Borogravia's Duchess, described (by herself, no less) as "only a rather stupid woman" when she was alive, but on her death was elevated by the prayers of her desperate subjects to a godlike force, albeit one with only the ability to move "small things". Now consider Vimes' offhand reference in 'Guards! Guards!' to the extreme unlikelihood of there being a God of Watchmen, what with it not being a very glamorous gig, and how Pratchett often likes to set these things up * decades* in advance. Then consider: Vimes as he is by the end of 'Thud!' is known to pretty much everyone as an unstoppable force. He's arrested a dragon, the Patrician, two whole countries, and he's fought trolls, werewolves, quasi-demonic dwarven rage beings, and the weight of history itself, and only lost to the last and even that was a close thing. Watchmen across the continent, in his own words, have been taught to salute him. He has earned the respect and loyalty of every Watchman in Ankh-Morpork, and they fear almost nothing quite so much as the prospect of his "going spare". It has been inferred by Angua ("Vimes puts words in his head") that a large part of the reason Carrot hasn't stepped up to claim his birthright is that "Old Stoneface" has very...specific views about kings, and Carrot is bowing to those views out of respect for the man as much as for the good of the city. He has the respect of both Diamond King of Trolls and the Low King (and the abject terror, no doubt, of any dwarf that claps eyes on the exit wound left on his arm by the Summoning Dark), and by now the majority of the smart undead, both local and Uberwaldean, have figured out that playing "les bugres risibles" with slow, plodding Vimes is a quick route to pain. And finally, he has Lady Sybil, who just plain loves and believes in him, and if he keeps his six o'clock appointments the way he's shown so far, Young Sam will probably follow suit. Likely result: Dunmanifestin is in for a very nasty surprise when Samuel Vimes bites it. Especially since, given that it's Vimes, he won't like it one little bit.
 * It's also worth noting that Vimes has effectively trained most of the watch officers all across the Sto Plains and up into the Ramtops, so he's already got a hell of a lot of believers/worshippers in potentia. In fact, I believe the generic term for a watchman was (as of either Fifth Elephant or Thud!) a "sammy".
 * If even Carrot is cynical enough to realize that no watchman would trust a self-proclaimed "God of Watchmen" enough to worship one, as he says in The Last Hero, what watchman is ever going to do so?
 * The problem with your refutal is the "self-proclaimed". Like most of the stuff that seems to happen to Vimes, if it happens it's just gonna happen to him (like the being promoted Commander of the Watch, Knighted and subsequently... En Duked?), he'll complain about it, mostly to himself, then just go on as if nothing happened. Even if he becomes a god, he'll still be a Watchman first and foremost. Plus, it opens up the chance for Vetinari to reinstate him in the Watch as "ethnic minority" (as he'd be, you know, a demigod), if only because that'd piss Vimes off royally.
 * It would begin slowly, first with watchmen and civilians from outside Ankh-Morpork simply not believing Vimes is dead, because Vimes cannot die if there are still things to be done -he'd go spare!-. So people would refuse to believe news about his death and would begin saying he is around, looking over people, specially looking over watchmen, not to protect them, but to see they do a good day of work. Watchmen would begin whispering that if you don't do your job properly, "Old Stoneface will go spare", and that he is bound to show up if things get too out of hand. Maybe it would all be an inside joke for the watchmen, up until the point when a copper is in a tight spot and the joke is the only thing there to keep him from giving up. Eventually, the knowledge of the fact that he is not alive would mix with the common sense that it doesn't mean he's gone. So it would not begin as worship but as respectful fear. "Who watches the watchmen?" "Well, Vimes of course! And death ain't gonna stop him!", and a bit of "WWVD?" So divinity would "happen" to Vimes in a similar, but not exactly the same, that it happened to the Duchess. Eventually, after a couple of years, all it would take would be for one copper to believe Vimes is keeping them safe somehow, and some fortunate coincidence happening, for the faith to become widespread very soon. Then Vimes wakes up one day on Dunmanifestin and goes spare because if being a duke is bad, being a demigod is simply too much, maybe he would even try going to the Disc to tell people to stop believing in him, and we all know how well that would work. And the beauty would be that there won't actually be a god of the watchmen, because a divine Vimes would not be likely to actively interfere with the day to day work of Discworld's watchmen. He would still be very bad news to those gods and anthropomorphic personifications who enjoy playing with people's lives.
 * Meaning he really would get to "arrest the gods for doing it wrong"? Awesome!
 * Alternatively, this troper can totally see him as becoming the anthropomorphic personification of The Law.
 * Smug Snake: "Who are you?" Vimes: "The Law you sons of bitches!"
 * This fic lays it all out brilliantly.
 * Given his reputation in Snuff, where coppers all over the Sto Plains seem to venerate him and even to non-law enforcement personnel, he's a household word, the evidence in favor of this one seems to be growing...

Sam Vimes Jr. will be the next Patrician
He is the son of the richest family in Ankh-Morpork, so the nobles wouldn't be able to complain that he 'isn't one of them'. He is being raised by Vimes, so he will probably be incorruptible. With his upbringing, he will be perfect for dealing with other races (trolls/dwarfs). Drumknott is being trained to act as his regent in case Vetinari dies before Sam Jr. is old enough to become Patrician. Moist will teach him what Vimes can't about dealing with people, and will probably be the poor sod who has to find all of Vetinari's secrets in the Palace. (And how to get into them. And how the route changes each day of the week.) If Carrot and Angua have a child, he or she will probably be his most loyal friend, which will mean that the obvious alternative (the latest 'heir to the throne') is not interested in fighting him.
 * Young Sam is really in the best position for this. He's got his parents, Carrot, Vetinari, and potentially Moist to learn from. You could even swing Susan Sto Helit as being part of his "education" if you wanted to. (fic for that.) Knowing Old Stoneface, though, about the only advantage Young Sam isn't going to get is an Assassins Guild education... but his selection of role models and "tutors" more than makes up for it. And imagine if Angua and Carrot had a daughter... If they avoid the problem of Unlucky Childhood Friend, then together they've got a lock on the patricianship and the throne (even if they'd be raised to believe that monarchy isn't how things should be done, they could still take advantage of other people's tendency to "bend at the knees" to secure their power base).
 * Any child of Carrot and Angua is going to VERY powerful Charisma-wise; people find it hard not to disappoint Carrot, and Angua knows how much good you can do with a smile.
 * Provided said child isn't born with fur, in which case it could well wind up as the new ruler of Uberwald. Assuming Nutt doesn't beat him/her to it.
 * I think Margolotta would have somthing to say about a half werewolf intruding onto her patch, no matter how charismatic.As for Nutt he seems to be expanding into a vimesey role, getting stuck into the messes personaly as opposed to giving the orders from the top.
 * There´s also such thing as personal union.
 * Vetinari is in his early fifties, give or take ten years at the most. Young Sam is a baby. Patrician, maybe; next Patrician, probably not. Although I guess it's possible; Vetinari's quite capable of lasting another two or three decades.

Detritus used to be a slab addict.
In his early appearences Detritus is apparently really dumb even by troll standards. He has worked in many different places and been fired from all of them. Later on he joins the Watch in an attempt to become more respectable and turns out to be fairly intelligent (sure, he has his special helmet, but can a cooling fan really make that much difference?). His hate for drug dealers also seems somehow personal. A possible explanation is that slab very nearly ended up ruining his life, or at least his relationship with Ruby.

Sam Vimes is being observed by the Green Lantern Corps.
For the cheap seats - the Green Lantern Corps are made of individuals with extraordinary willpower. Vimes defeated an entity of pure malevolent rage that is an untold age with willpower alone. The only reason they haven't come for him already is because Vimes still doesn't trust magic one bit, and put yourself in his boots for a moment - if you saw a flying green ring bearing down on you, what would you think?
 * More likely the Guardians have had to actively program the rings such that Vimes could never become a Green Lantern. A man basically built of a pure willpower core with a few scraps of meat attached is fine, but he's also completely anti-authoritarian (despite being a figure of authority himself)--would you want to walk up to him and say, "We've decided that we (and only we!) have the authority to run the galaxy, because we're older and smarter and better than the rest of you idiotic children. By the way, here's a ring of limitless potential that can do absolutely anything you tell it to do." Vimeses have a habit of doing bad things to leaders that they suspect don't have the best interests of their subjects at heart—Wolfgang, Lorenzo the Kind, Lord Rust... the ones that survive don't do it happily.
 * The Guardians have had quite enough of that from Alan Scott, who has a ring but isn't a Corps member (and both sides are happier that way). They really don't want to deal with another one.

The Summoning Dark is the Red Lantern (Rage) Entity.
The readers were never told what the being looks like, only that the symbol resembles an eye with a tail.

Carrot's Sword is magical.
In The Colour of Magic, Rincewind mentions heroes tend to carry unprotected magic swords that mess with all nearby magical experiments. A king would live in the city, so it would be pretty important not to mess with all the magical experiments that they ever do. As such, his magic sword would be protected. Possibly so well that it emits less magic than a normal sword.
 * Carrot's sword is magical in the same sense that absolute zero is a temperature.

Carrot's sword is immune to tropes.
That's what makes it so dangerous - it doesn't care what it should be doing according to the Narrative Convention. It just cuts things.
 * Canon, except for the phrasing of the title line. It's real, it's just a sword, and in being so on the Discworld, not just a sword, but a sword. It's not as fluffy magical as everything else on the Discworld, it's a sugar-glass blade in a candyfloss world. As you said, it doesn't care about the narrative convention, i.e. tropes as expressed via Narrativium. It just cuts things.

Carrot and Vimes are the Good and Bad Cops.
As in, the actual personification of them. Vimes inshakable will is the reason he has not given into his purpose, struggling against his destiny. Carrot was left for the dwarves to raise like Lobsang Ludd/Jeremy Clockson were left at the Thieves' and Clockmakers' guilds.

Sir Samuel Vimes is "Old Stoneface" Suffer-Not-Injustice Vimes.
Following the same logic as in Night Watch, Vimes is switched out with his ancestor's corpse and goes through the entire rebellion as him, eventually decapitating King Lorenzo.

Carrot's adoptive parents are both the same biological gender.
At one point Carrot says he's almost sure his mother's female. Which would leave room for doubt even if he was sure his father was male. Since traditionalist dwarfs are determinedly uninterested in each others' private lives and unaware of each others' gender, there's no reason they would subscribe to human perceptions of sexuality. As far as they're concerned, a dwarf is a dwarf. Sometimes dwarfs fall in love and get married. Sometimes they then have children. Sometimes they don't. The whys and wherefores are their business, and Carrot's parents do not seem to have children (except for the one they adopted).
 * ...That's brilliant. Carrot's adopted! (Not sarcasm, it's just so easy to forget he's not biologically a dwarf, despite being over six feet tall with no beard to speak of and .) In one of the earlier books where dwarf sexuality is mentioned, one of the steps (the one after getting married) is to hope they're right.
 * Actually what Carrot says is that he's almost sure his stepmother is female. Whether this means that his father remarried at some point, or he's just using the term to indicate that she isn't his biological mother is unclear.
 * Probably the latter, as it's apparent from his conversation with his adoptive father in Guards! Guards! that the dwarf Carrot knows as his Mum is the same one who became attached to him when he was found.

One of these days a wizard will join the Watch.
Because the universe seems determined to make Vimes hire people he doesn't want in his Watch. Now that he's got a vampire, there is only one hurdle left to clear.
 * That does seem possible, although the universe would have to work quite a bit harder even though Vimes is not strictly prejudiced against wizards the way he is against vampires. As wizards try not to interfere with the ordinary working of the city anymore, and Vimes (and presumably Vetinari) would not like magic used in policing in the sense of 'magic [criminals] into cells...wave a wand to find out who's guilty...magic men good' (from Thud), then a wizard in the Watch would only need be used as a sort of liason, to step in whenever a magical crime occurred in the city. As this is presumably something the wizards would already come down on, or the Watch would inform them of if it happened, there would seem no need for such an officer. I wouldn't be surprised if Ridcully joined the citizen's militia though (I still love how the President of the Guild of Thieves is a special constable of the Watch via the militia).
 * Already done. The Librarian is an auxilliary member of the Watch, and if you've read The Light Fantastic, then you know he IS a wizard, albeit morphed.
 * It'll be Rincewind. Technically a wizard, but no fear of abusing magic at all!
 * On account of how he really doesn't have any!
 * Or at the very least, nothing that's useful.
 * Only it'll be one of those honorary paper badges, like they give little kids, and the Librarian currently has. Although, mentioning the Librarian...
 * Not only is the Librarian a Special Constable, it is mentioned in Men at Arms that the University Dean tried to join the Militia. If a wizard does get involved in the Watch, the Dean is not to be ruled out.
 * Jossed by Unseen Academicals, as the Dean has moved to Pseudopolis.
 * Then again, Vimes has mentioned before that he likes the Wizards, mainly because the problems they cause tend to have nothing to do with the city's laws, and don't lead to paperwork.
 * CSI: Ankh-Morpork
 * "Foul Ole Ron told you, then? Did he mention... * Glasses Pull* shrimp?" YYYYYYEEEEEEEEEEEEEAAAAAAAAAAAAHHHHHH!!!!!
 * Didn't the series go there when Cheery Littlebottom joined the Watch as a forensic alchemist? * imagines Cheery in black lipstick and her hair and beard in pigtails*
 * Nah, that'd be NWCIS (Night Watch Criminal Inbvestigative Services).

Sally was once a human.
She seems to be a grown up vampire, but is actually only in her fifties, much younger than the "teenage" Lacrimosa. Since you can either be born a vampire or become one after being bitten by one, the most reasonable explanation is that Sally was bitten as an adult or teenager.
 * she cant be: vimes asked her about her family history and she specificly mentions that the only thing that runs in her family is biting.
 * Perhaps her family adopts rather than having children? Quite literally, bites are the only thing that run in her family—their 'children' are bitten. Possibly orphans or something else, since Sally appears to consider this her family, not a replacement.
 * I believe Count Magpyr was the reason Lacrimosa never aged past her teenage years, I can'r remember the quote but Lacrimosa argues with her father when she finds outr she'll be a teenager forever.
 * Or maybe Lacrimosa acts like a teenager because she's a spoiled bitchy brat, and she appears younger than Sally because she just happens to look young.

Nobby is an orc
His physical description isn't a great way from that of  - a short, ugly humanoid with a talent for not dying. Much has been made of nobody being quite sure Nobbs is human, and he seems to be considered human mostly by default, as no other race has claimed him - orcs haven't been around to do so. His unpleasant behaviour is also a bit closer to his ancestral calling than the carefully-conditioned.

Vetinari knows it, which is why Nobbs hasn't been kicked out of the watch despite his thieving. When a new ethnic group starts to have a strong presence in Ankh-Morpork, Vetinari tends to insist that one gets hired by the Watch. There are plans to make contact with the lost orcs in Uberwald, and Vetinari expects a wave of orc immigration after that - so, being able to reveal that there's already an orcish watchman will save him a long argument with Vimes one day.
 * Furthermore, in Snuff, a female goblin takes a very great liking to Nobby, as she thinks he's quite attractive. The goblin tribe, in general, readily accepts him. And Nobby, in return, is quite flattered and gets on well with them. Orcs and Goblins are often portrayed as getting on extremely well (if not two branches of the same family tree) -- in some settings, hobgoblins are actually what happens if an orc and a goblin mate.

Terry Pratchett is a male witch
Mistress Weatherwax said warlocks exist. Terry meets the criteria. He codified headology; shares Mistress Weatherwax's fondness for dark attire; Mis Tick’s covert style of headgear; Maggrat’s taste in wiccan accessories; and Miss Level’s (Levels' ?) belief that stories are more effective than preaching. Like Nanny Ogg, he is so advanced he doesn’t use magic. Like Granny Aching, he isn’t even aware of it, nor would he ever admit to being one. Also - Just look at him!

Also, The Disc was created by Magratheans.
Why NOT?
 * Er, because the Creator didn't mention anything of the sort in Eric?

The Igors are a type of Golem.
Flesh golems, to be precise. The Igors were an attempt at a more intelligent, but still obedient golem.


 * Under the right circumstances, Igors are extremely, inhumanly competent, on a similar level to actual golems. In Monstrous Regiment, for example, an Igor is described as performing a series of complex surgeries (limb reattachments) in a few seconds, moving so fast that its hands are blurred and almost invisible.
 * Igors follow orders unquestioningly (90% of the time), just like golems.
 * Igors feel a pathological need to have a master. The closest we've seen of an unmastered Igor is the coroner in the watch (who calls Vimes master at first) and the Igor in Monstrous Regiment, who still follows orders from a master figure (Jackrum).
 * The more recent trend of (sort of) unmastered Igors may indicate another golem revolution ala Feet of Clay.

Igors are not called golems because when golems were still being produced, as we're told in Feet of Clay, it was done so by priests, so a golem made of flesh—and with a voice at that—would have caused some significant problems for its "employer". Presumably, he or she passed their new creation off as a funny-looking lab assistant. The Igors' knack for surgery is due to their need for "self repair" being made of what are essentially secondhand materials.


 * Except that Discworld uses the original ancient Hebrew rules for Golems, not the Dungeons & Dragons ones.
 * I didn't read that as having to do with Dungeons and Dragons, nor was that how I wrote when adding to the guess. A clay golem is a statue made of clay, bought to life by Divine power. A flesh golem (under the premise of the guess) is a statue made of flesh and bone, brought to life by an unknown power (in D&D, either Arcane or Divine power, and in this case by ''Science!) What's the problem?
 * Igors still reproduce biologically, though, and can be killed without special means. Golems are made of inanimate materials brought to life, whereas Igors are living beings that just happen to acquire a few replacement parts over a lifetime.

There is an Illuminati like group of figures now running the entire Disk.
We can imagine that the idea came roughly 30 years into the Disk's past, set in motion by Lady Roberta Meserole (Vetinari's Aunt) and Lady Margolotta (Vampire). This plan included getting the peoples of the disk to become more friendly, as in the 30 years since they began the Dwarfs, Trolls and undead are all significant minorities in the fastest growing city on the Disk. They set things up so that the people hated their current ruler (Lord Snapcase) so much that they elected someone who seemed to be sensible, if not well known (Vetinari).
 * With Vetinari in charge of Ankh-Morpork, the city has started to pull it's socks up, figuratively speaking. The Introduction of the guilds, the revival of the City watch and Post office, carefully setting up Moist Von Lipwig for his future place in the secret organization.
 * Don't forget he restored Ankh-Morpork's dominance of the Sto Plains, turning the other cities, it has been said, into smaller versions of Ankh-Morpork, thus making his contribution even more widespread.
 * Lady Roberta Meserole (Still alive in making money, mentioned in passing my Cosmo Lavish) is running, (probably indirectly) the state of Genua, where she has numerous 'significant pause' business interests.
 * This troper wouldn't equate living in Genua with running Genua, even for one of Vetinari's kin. Genua has Ella as its rightful queen now, and she's descended from  on one side and (probably) General Tacticus on the other.
 * Lady Margolotta is carefully running things in Uberwald, placing a (possibly female) Human friendly Dwarf into the position of Low King, and has helped to stabilize the whole area, as we can assume from various accounts, most notably Lipwigs, that until recently the whole of Uberwald had been in various states of turmoil.
 * Mustrum Ridcully, Archchancellor of the Unseen university, has single-handedly put a stop to the wizards murdering one another and has (by obfuscating stupidity) rallied the faculty, (particularly the promising Ponder Stibbons, another future candidate for a position in the illuminate) into becoming more or less useful, as well as not only contacting Fourecks, but establishing friendly relations with a country that until then had been deemed us semi-mythology.
 * Now here is where my theory requires a bit of a stretch, but I feel the following should be included by necessity.
 * Mistress Esmerelda Weatherwax. Witches are forbidden to influence Kings and such but it becomes plausible when you consider the influence she has indirectly had thus far. She may be merely working as the Illuminati wants her to, whether she knows it or not, or she may be one of the members, depending on how much you feel she is actually a lot smarter than anyone ever gives her credit for.
 * It's practically canon that "witches are forbidden from interfering in politics" is as much a fiction as "witches don't have leaders (because Granny Weatherwax says so)". Verence seems quite clear that the witches will never interfere in his decisions as long as he never makes any decisions they disagree with.
 * This troper would like to point out that Granny is far too crotchety to work with a group, and thinks Nanny Ogg is a far more likely member. She could manipulate Granny into doing their will easily.
 * Granny is too arrogant to take orders or work with such a group. More likely, she knows of them and either plays along for her own reasons or simply finds that their goals and hers coincide.
 * Twoflower. When he helped Rincewind save the world for the first time, they recognized his usefulness, and decided to keep an eye on him. How much of a stretch is it to consider that Mister Saveloy was sent as an agent to the silver Hoard, to send them to the Agatean empire and get them to open up a little. After Cohen inevitably got bored and left, Twoflower was conveniently left as Grand Vizier. Is he now working as an agent for the group?
 * Alternatively, considering how long ago the first two books were (before Vetinari, certainly), it was Twoflower who set the whole cabal up, and his "vacation" around the disc was secretly a cover for doing so. Consequentially, Twoflower is effectively ruler of the Disk, and, as nobody knows this (possibly not even the group itself, which he may have manipulated into formation during his Summer Vacation without their knowledge of his manipulation), nobody can overthrow him. It goes without saying, then, that his is Obfuscating Stupidity.
 * I'm pretty sure the first books were officially not pre Vetinari. And even if they were, he was manipulating politics since Vimes was first on the watch. He'd know.
 * This troper distinctly remembers Vetinari assigning Rincewind as Twoflower's guide in Color of Magic, so the first books are not pre-Vetinari. They could conceivably be early in the Patrician's career. Small Gods is the only book this troper can think of that is pre-Vetinari, being set roughly a hundred years before the rest of the series.
 * That was "The Patrician", not Vetinari. We know it wasn't simply an uncredited Vetinari appearance because The Patrician was described as being fat, something Ventinari never was. In all likelihood, it was probably Snapcase, who was replaced soon after.
 * Pratchett himself has said it was Vetinari, just Vetinari written by a younger, stupider writer. The BBC adaptation of the first two books has a Patrician that is clearly meant to be Vetinari (thin, wears black, pets a small dog...).
 * People being used by the group as tools for the furtherance of their plans for a unified Disk.
 * His Grace, Commander Sir Samuel Vimes, Duke Of Ankh, Blackboard monitor. Combined with the next person listed here, he has been instrumental in reviving, and reforging the City Watch, modernizing it, and turning it into an effective police force. He has also been instrumental in foreign affairs, stopping a war with the Klatchians, Getting Borogravia to surrender and ally itself with AM, and saving the life of the Low King, before helping to settle all that silly Koom Vally business, and not forgetting that he also got the Device for AM, so Vetinari could begin 'The Undertaking'.
 * Vetinari has more-or-less spelled out that he uses Vimes as an unwitting enforcer. Vimes's personality is so predictable that every situation he's put into becomes a Batman Gambit.
 * He messes up a few minor plans on occasion, but that sort of thing tends to work out anyway.
 * Captain Carrot Ironfounderson. Heir to the throne, natural leader, able to not only see the best in people, but bring it out in them too. He helps Vimes revive the Watch, knows who he is and what he is, and still decides that for the good of the city that he should do an honest day's work. Why was he left alive by the bandits who killed his parents? Why was the royal sword left behind? It's not inconceivable that Lady Margolotta was keeping an eye on him, and had him protected, but either let his parents die, or didn't get there in time. She could also have alerted Carrot's adoptive dwarf parents to his location.
 * Or Granny. It's known that the Ironfoundersson mine is in or near Lancre: Magrat gets mentioned in Guards! Guards! as the nearest person who knows about spelling, and in Lords and Ladies it's proposed that the captured elf be turned over to Carrot's dad for disposal.
 * On the other hand, it could be argued that Carrot is actually using Vetinari, since it is heavily implied he's keeping his identity secret for only as long as Vetinari does a good enough job that a great king isn't actually needed as much as a good policeman.
 * Note that, since The Last Hero, Carrot himself is world famous, being the most photogenic member of the spaceship crew. And one who faced down Cohen and the Silver Horde, no less.
 * Moist Von Lipwig. Single-handedly (with provocation and threats of death) revived the Royal Post Office in a matter of days, before sorting out the crumbling economy, again in a matter of mere days. This fits with the theory that he is being groomed for the patricianship, (and possibly more) by Vetinari.
 * Tiffany Aching. Recognized by the Nac Mac Feegle as possessing the potential to become the 'Hag of all Hags' it is not unlikely that she, like Lipwig by Vetinari, is being Groomed by Granny Weatherwax for a position in the group. Probably Granny's own.
 * King Verence II of Lancre. He seems quite keen to make ties with other nations and become part of the Discwide community. His most notable attempt to do this was a disaster (Carpe Jugulum), but that's because he slipped the witches' leash and attempted it on his own bat.
 * Under this hypothesis, William de Worde and the Ankh-Morpork Times might also be a significant factor in the conspiracy. Not necessarily as a tool of the group as a whole, but as an ace in the hole that Vetinari can use to checkmate the other Illuminates, should they get out of hand, by arranging for any schemes he disapproves of to get exposed in the press.
 * No, no, you're all getting distracted by the main characters! Vimes got it right: it's the wives of all the Disc's powerful men who are really running things, and have been all along!
 * Then, logically, their greatest rivals would be the Borogvian Military High Command. Could be the real reason Vimes was sent there.

Burke is Altogether Andrew's true personality.
Why would so many minds make such a concerted effort to keep him down?
 * So where does the name Andrews come from? None of them answer to it.
 * Burke Andrews? And sure, he may seem violent...but how would you feel in that kind of situation?
 * I always thought Altogether Andrews was just a collective name conferred by the other beggars. It's allili- alirili- ariter... they both begins with the same letter!
 * As to where it came from, this is the same group of beggars that called Death "Mr Scrub" in Soul Music. "He didn't know why. On the other hand, he was among people who could hold a lengthy conversation with a door."
 * “Jossi, Lady Hermione, Little Sidney, Mr Viddle, Curly, The Judge, Tinker and Burke. They’re called all together Andrews.” But in Honorary Beggar’s Guild Member thinkspeak.
 * On a side note, did anyone else just catch the Stealth Pun reference to Reaper Man?

Hex will become linked to the Library, and thus become as close to all-powerful as is possible within the stories.
Only all-powerful for a short time, mind you. Hex can already look up fragments of books that don't quite exist, and L-Space has all of the books that exist and most that don't. This ability will link Hex to L-Space (with a Shout-Out to the L-space online community), and Hex will become far more powerful, as he is able to instantly look up the grimoires in the University library, and elsewhere. One of the nonexistent spellbooks he will look up will be the way to unlock Whoever's Fantastic Garden from the outside to release the now-20-year-old Coin with stable powers. After the events of the book are solved, Esk will accompany Coin back to his pocket dimension, and Hex will take over running the city and helping the Librarian with the increase in power from using all electronic card catalogs in existence for extra RAM.
 * I thought Hex did get an L-space connection as part of the Roundworld Project?
 * He did. Hex probably is as close to all-powerful as it's possible to get: he's just far too smart to admit as much to the wizards, who'd then see him as a rival rather than a useful piece of equipment.
 * Speaking of which, Hex is later reincarnated in another universe as Deep Thought.
 * But they forgot to FTB-enable him, so the whole Answer thing got a bit...

Susan really is Helpfulness Personified
It'd explain a couple of things. Like the fact she keeps doing things for the world's benefit in spite of arguing in Thief of Time that she does NOT have a nice nature, damn it. Besides, it's not like it's the weirdest personification out there...
 * Well, she's something personified, at least.
 * maybe sarcasm?
 * Good one. Or skepticism, maybe.
 * Pragmatism.
 * No, Helpfulness. But she gives you the help you NEED, not the help you want.

The disc from Strata is the Discworld in the future.
At some point in the future, The Magic Goes Away (this process might have started already). Since the Disc as it is now can't function without magic, there is a supreme magical overhaul that recreates it in a more physically-possible form.
 * Alternatively, when Hex writes ++ Recursion is occurring.++ at the end of The Science of Discworld, he isn't referring to Terry Pratchett writing the Discworld books, but to the creation of the disc of Strata...
 * Or maybe Hex mentioned the "recursion" when he took a look at the Roundworld extelligence's corner of L-space, and found the works of a certain Terry Pratchett. Meanwhile, in the far reaches of Roundworld space, some human components of that same extelligence ("As above, so below") found those very same works on a database of literary classics, and decided that they now knew exactly what shape to make the new artificial world they're contructing....

The Eighth son of the Eighth son of the Eighth son of the Eighth son of the Eighth son of the Eighth son of the Eighth son of the Eighth son would result in...
...Terry Pratchett
 * He's an only child.
 * In this world, maybe, but he was really born on the Disc, which couldn't handle that much magic, and the laws of reality were forced to extrude him into another world (ours) in the role of supreme god of the Disc.
 * So Roundworld is Pratchett’s accidental version of Maligree’s Wonderful Garden?

The Rite of AshkEnte has been deliberately Bowdlerized over the years, to the mutual benefit of everyone involved.
The recurring Death-summoning ritual is described as requiring a vast amount of the typical magical summoning apparatuses, or more simply with several sticks and an egg or mouse blood. But even the method used by the wizards has been toned down. After all, if the proper rite was cast, Death would truly be bound in Unseen University, potentially causing worldwide problems and irritating him in general. Thus they use one of the lesser methods instead, one that costs them a great lesser deal of resources and doesn't actually bind Death (he's made it somewhat clear that he sticks to his part of the rite out of politeness), though being significant enough to require his attention. Incidentally, Albert went through the whole shebang when trying to invoke the rite backward. He couldn't be too cautious.
 * On the one hand, Susan in Soul Music is summoned and can't get out of the circle until Ridcully lets her out. On the other, on at least one occasion Death has shown up outside the summoning circle surprising the wizards. Maybe he just has a better sense of his schedule and shows up early to disrupt the ritual?
 * Alternatively, Ridcully knows the right Rite but none of the new wizards do. Would YOU teach younger wizards how to summon Death?
 * It doesn’t benefit the mouse or the chicken foetus.

The meaning of ha'ak
How can we not already have this? Anyway, starter suggestion:
 * 'ak seems to be a negating ending (cf. drudak'ak). When designated progressive Bashfullson uses ha'ak towards Ardent in Thud!, it at first seems out of character, since ha'ak has so far been implied to be a term of abuse used by reactionary types against "out" females. In context, though, it seems to connect with his (?) challenge to Ardent to "Show yourself! What do you believe in?". Which suggests that ha'ak literally just means something like "not hiding" or possibly specifically "not hiding their sex/gender", even if it has acquired negative connotations, and also that .  . This is all assuming, of course, that nobody, including Pratchett, has come up with an official explanation (or a whole worked-out Dwarfish Ã la Tolkien) that I've somehow missed.
 * I had a theory that explained it as a corruption of d'harak (not-dwarf, including humans and trolls rather than specifically dwarfish blood traitors), the "d'-" noun prefix meaning "something that is" (as opposed to "something that isn't" or "something that is so not I don't even what"), and "-'ak" or "-ak" being a negative (so [drud][ak]'[ak] literally translates to "[surface-seeing][not]'[not]", assuming Dwarfish negatives stack instead of cancel, or "one who does not get out in the fresh air enough" for a less respectful translation)... Anyway, I went from that to working out the basis of possibly the entire Dwarfish language. The short of it is, it's a very, very rude way to call a dwarf not-dwarfish, which in itself is a powerful offense and, if not contested, dishonor. This is why it has mostly been applied to female dwarfs (as opposed to those whose gender equals "Dwarf" and just happens to have what I would assume is a uterus. See Lady Sybil's "they're both dwarfs" in regards to Bloodaxe and Ironhammer. For example, a very rude dwarf might call Casanunda a "ha'ak".)
 * Then again, Casanunda seems to advertise his male gender (unless we really need to go back and do a serious double take for all his scenes, let alone the admittedly broad-minded Nanny Ogg's reactions to them) pretty overtly, so wouldn't that still be covered by the idea that "ha'ak' means something like "uncovered", "out of the closet", "unduly advertizing their gender"? If there is a whole worked-out account of the dwarfish language somewhere, though, a link would be great (Canon or Fanon, but it would be nice to know which).
 * Here is a not-quite-exhaustive list of canonically explained phrases ("not quite exhaustive" not including the two terms introduced in Unseen Academicals, at least one of which is almost definitely a loanword from Morporkian, there are a few words from older books not on the list- it's a pretty good resource, though).

Andy Shank is Carcer's bastard son.
They're not just psychopaths (which is a somewhat heritable trait anyway), but the same kind of psychopath: where the rest of the series' villains are either Well-Intentioned Extremists or obviously threatening psychos with a Red Right Hand, Carcer and Andy are both described as fundamentally normal-looking, sadistic, and the kind of person who'd kill a man in the middle of a crowd and expect to get away with it. Provided that Carcer's at least in his early thirties in Night Watch and Andy's not past twenty in Unseen Academicals, the ages work out plausibly. The only real problem with this is that there are a few mentions of Andy's dad, who is most definitely alive, well, and not (exceptionally) wanted by the Watch five or six years after Night Watch, but all that absolutely has to indicate is that he believes he's his wife's son's father.
 * Alternatively, Mr or Mrs Shank is Carcer's child with a woman he met while in the past, making Andy Carcer's grandson instead.

Magical ability does not know gender
If I'm right, some people are born with innate magic; but there is not anything keeping the individaul from being a with (or warlock) or wizard (or enchantress) except psychology, since the two schools of magic require a particauler mindset you can't be both. Witchcraft and wizardry are almost exclusivly practised along gender lines because of predudice, a person thinks they must conform to the magical norm. And I have proof, in the Colour Of Magic, the archchanncelor is a Weatherwax a brother a cousin, who knows, but he is related to everyones favourite witch, suggesting that the weatherwax clans magic isn't any specific sort it's just magic.
 * How is that proof of anything? Granny doesn't use Weatherwax magic, she uses witch magic. And whatever Lily uses isn't witch magic at all, and not really wizard magic either, so 1) this is pretty much proof that the typoe of magic you're naturally adept at, if anything, has nothing to do with the family you were born into, and 2) enchantress magic isn't necessarily female wizard magic, as Granny implied in Equal Rites, especially since warlock magic (the other magic she referenced in the hand wave) has nothing to do with witch magic or headology.

Bes Pelargic, the Agatean port city Twoflower is from, is suspiciously American rather than suspiciously oriental
Thus neatly explaining both why the rest of the Agatian empire sees people from there as weird and why Twoflower was an American-style Hawaiian-Shirted Tourist in the movie adaptation.
 * More likely he picked up the shirt in the islands, while waiting for a ship to Anhk-Morpork. They aren't called Hawaiian shirts for nothing, and we know Twoflower is addicted to kitsch.
 * Actually, it may be that Bes Pelargic is Hawaii. Hawaii's largest ethnic population is Asian. It's also very strongly associated, for North Americans and some Asians, with the tropes of tourism.
 * I thought Bes Pelargic was Hong Kong.

Mustrum's love of hunting comes from his chasing of Esme all those years ago
Archchancellor Ridcully and Granny Weatherwax may not have ever properly gotten together, but we know their relationship left a profound mark on both of them. She still has his letters, and even years and years later he remembers her without any prompting, if not her name right off the bat. It stands to reason that the way Mustrum acts about hunting things down and shooting them with the crossbow is repressed disappointment over never able to catch Esme. I'll leave the crossbow bit to your imaginations,I'm sure you can catch my meaning. Consider his phrasing that he'd have 'wed her like a shot.' Obviously he's still frustrated over it, and all the better, he'd have never made Archchancellor without those qualities, he'd have given up wizardry anyway, and UU certainly needs him. Maybe Esme knew that?
 * Or, on a nastier note, he started hunting because Esme dumped him, and he wanted to get even. He knew about her talent for Borrowing the bodies of animals, so began shooting every woodland creature he saw in hopes that she was riding in his target's mind and would share its pain.

"Bloody Stupid" Johnson was an extreme inspiration-magnet.
We know that inspirations in Discworld are like subatomic particles, and that certain people (Hwel, Leonard of Quirm) get struck by them more often than others. The sheer breadth of "Bloody Stupid" Johnson's failed creative endeavors suggests that he, too, attracted lots of the pesky things, he just couldn't keep straight which was which. Hwel and Leonard both seem to fall prey to Johnson-like behavior at times, as when Leonard's inventions wind up being something completely different from what he'd intended. But while those two can compartmentalize ideas enough to figure out that, say, Laurel and Hardy jokes don't belong in a play about gruesome murder, and edit out the incongruities, Johnson tended to merge bits of two different inventions in the actual construction process, with catastrophic results. The fact that he regularly confused inches and feet suggests that his brain wasn't much good at keeping its data sorted, causing Johnson to meld incompatible inspirations together, giving us plumbing/pipe organ hybrids and mail-sorting machines based on purely theoretical physics. In short, he wasn't so much "stupid" as suffering from inspiration-overload.

"Bloody Stupid" Johnson is Leonard Da Quirm's insane alter ego.
Perhaps he's a vampire as well, whose personality is inverted during the day.

The Undertaking is going to be the Disc-equivalent of the Underground.
Ankh-Morpork already bears many resemblances to London. The dwarfs use tunnels under the city to get places faster, and as of Thud! the mine sign to mark the entrances is a circle with a bar through it—the Underground logo. Leonard could invent the trains, and they could be powered either by the Device or by some of the golems that Adora Belle found in Making Money. Even the names fit!
 * I don't think that's "wild mass guessing." I think it's foreshadowing.

Susan's life is a huge Batman Gambit.
Susan exists solely because Death needed someone with his powers, who wasn't bound by the restrictions that come with being a personification of belief. This is why Death saved Ysabell and trained Mort as an apprentice: In the hopes they'd hook up and have a kid. Being Death, he probably knew how it would work out from the very beginning.

Madame Sharn made/designed the rubber and leather dress mentioned on page 137 of Unseen Academicals.
Because some things are too perfect not to be true.

Carcer is still alive.
Think about it. He was sentenced to hanging. Now let's see, which other characters were sentenced to hanging? There was 1) Rincewind, in The Last Continent. Excaped and saved the country. 2) Moist von Lipwig, in Going Postal. The hanging is faked by Vetinari, because he is useful, and he ends up as head of multiple large business organizations. 3) Owlswick Jenkins (in Making Money) is rescued and then secreted away by Vetinari, presumably to make something artistic that is very necessary, somehow.

Now, who else has gotten the angel treatment? Moist von Lipwig, the incredible thief. Reacher Gilt, expert swindler and crooked business man. Owlswick Jenkins, stamp forger. So Vetinari only does it for normal thieves, not murderers, right? But doesn't it say, in the book, the whole "Would you let a murderer go for a thousand dollars?" passage? It's the same thing. What are Carcer's skills? Firstly, he's charismatic. He is said to almost be able to convince you that he is innocent. Secondly, he's super-sane. That's more or less the whole point. Why the hell wouldn't Vetinari take him? Remember, Vetinari is compared to a little old lady who collects pieces of string, because they might be useful. Every time throughout the book he comes up, he counsels towards the perfect arrest. In the second scene, he asks that shouldn't Carcer be taken in by the book, and says "and ask questions later." He knows Vimes perfectly. He knows that Vimes just wants to kill Carcer. He is subliminally convincing hhim not to kill him. In the graveyard scene, there are three hints. One, on the same note, he congratulates him on a perfect arrest. Two, there is the "What could I prove? And to what end would I prove it?" He is telling Vimes not to pursue this line of inquiry anymore. Vimes's life as Keel is over, and Carcer's life as Carcer is over. Thirdly, "The Job they had to do." Vetinari needs Carcer for something, and he will make him do it. I don't yet know what it is, but I feel like he will come up again. We never see him die. All we see is that he is sent to the gallows... and disappears.
 * Carcer is almost completely uncontrollable and doesn't believe in authority capable of harming him. He just kills who he likes, or whoever's in his way at the moment. His Watch career was simply a joke on Vimes. There's no way that even Vetinari could ride herd on such a man, and Vetinari must know this.
 * In addition, what task would Vetinari have spared his life for? Carcer's a Complete Monster first, and those...unique skills haven't been useful since the days of Lord Snapcase. Plus we know that the city really does hang some people—remember, after Moist rescues Owlswick Jenkins from the Tanty, Vetinari has to execute another prisoner in his place, and there's no indication that guy didn't really die. (This from Carcer's biggest fan, for the record.)
 * If Vetinari needs someone killed (which is all Carcer would be much good at), he's already got a palace full of "dark clerks" to take care of that. Most of them are scholarship graduates of the Assassins' Guild, and a lot better-trained than some psychopath off the streets.
 * Carcer is a cop-killer who threatened Vimes' family. Sparing his life is, without question, the one thing Vetinari could do to permanently turn Vimes against him, and the Watch commander is a much more valuable asset to the Patrician than Carcer could ever be.
 * It is possible, Vetinari being Vetinari, that Carcer is currently tied up in a solid iron straightjacket with one of those Hannibal-Lecter face masks, chained to a really thick pillar with a dozen heavy chains, inside a stone-and-octiron cell deep, deep under the ground where it can only be reached by going through a series of fortified tunnels practically-overflowing with DaQuirm-designed deathtraps, guarded by a phalanx of those Umnian golems whom Vetinari has somehow convinced to answer to him and only him. Having faked the man's death so well that even Vimes wouldn't notice. Just in case he ever encounters a situation that can only be solved by a man with even fewer morals than Vetinari himself.
 * Except Unseen Academicals shows that you can find people as psychotic as that on any city football squad.

The phrase "ton of rectangular building things" is a troll euphemism.
It gets used because the term 'brick' is a troll insult, something along the lines of uncle tom, possibly. This is presumably why Detritus is so protective of and touchy about the character of the same name in Thud!

Coin turned Wuffles back into a puppy at the end of Sourcery.
It's the one thing Coin could do to make amends for letting Vetinari get turned into a lizard, that the Patrician would appreciate on a deeply-personal level. It resolves the quandry of Wuffles being age 16 in The Truth, despite his having been described as elderly in Sourcery, which took place well over a decade earlier. And, hey, most boys Coin's age like dogs.

The whole series is a game of wits between Fate and the Lady.
This was set up from the beginning. The two gods have had a rivalry for years, and this takes the form of the various stories throughout the series.

The Lady is Rincewind's mother.
So far as I can remember, all Rincewind says about his mother is that he is aware that he must of had one, but that he doesn't remember her at all. It would explain a) his ability to survive even when he isn't being used as her game piece, and b) her apparent personal interest in his success, as she has appeared in person to help him, which would seem to go against her nature of killing people who believe in her (it seems as well, that he actually recognized her in The Colour of Magic, which means it wasn't the first time he's seen her).
 * Actually, what he specifically says is that she ran away before he was born, but that's more or less too confusing to be admissable. I've seen a fanfic on these lines.

If Terry Pratchett dies in the middle of writing a book, Neil Gaiman will finish it.
He's a good friend, he's the only person the readers will accept, and he almost finished The Salmon of Doubt, or so I hear.

Ridcully is an either an avatar of or a god of the hunt
Quoth Lords and Ladies: "gods of the chase, who tended to be hearty and boisterous with the tact of a tidal wave. Sound familiar?

The Dean (Henry) would have become Archancellor of UU but was 'skipped' in favour of Ridcully because he behaved especially badly during the events of Sourcery
This is why he butts heads with Ridcully so much, because he feels he was denied his 'turn'. Interesting Times also states that (though not Dean) he was very 'senior' at the time.

Mr. Slant died during or just before the Civil War
The reason why king Lorenzo was executed without a trial was that there were no lawyers willing to get involved in such a trial. But surely Mr. Slant would do it if he was paid enough. In Making Money he is stated to be a little over 350 years old, so he was probably around at the time. Unless, of course, he was dead.
 * It may possibly be that 'no' lawyers was a little bit of an exaggeration, and that what was meant was 'not enough persons with judicial training to actually have a trial'. After all, Slant may have been willing to appear as prosecution or defense, but that leaves someone else to take the place on the other side - and, of course, you need a judge, as well.

Golems were invented by dwarfs.
Dwarfs believe words have great power and treat written words like something almost alive. A creature powered by words just fits really well into their culture.
 * This works particularly well when one considers that the Discworld dwarfs are considered by many readers to be a bit Jewish, since that's the mythology from which golems (in their relevant form) originated.
 * Dwarves bang on about not having priests a few times, though. I'm sure they otherwise love the idea of eternal words guiding things.

On the Disc, Cosmic Retcons leave pieces of the original time line lying around.
We know that the History Monks were somewhat inexact when they pieced history back together after the Glass Clock shattered. Someone got a few bits of the original time line of Soul Music mixed in with the "official" time line. Luckily, the pieces that got put back in were fairly innocuous, and resulted in a few people remembering things they should have, rather than The End of the Disc as We Know It.

Rincewind's first name is Trevor.
A ginger wiz(z)ard who gets into trouble wherever he goes? That sounds familiar....

Rincewind's first name is Willard.
Those aren't Zs, he just rolled with people's misreading it after a while.

Shawn Ogg will have a wizard for a child someday.
We know that the eighth son of an eighth son is automatically a wizard. While this statement specifies that the wizard's father must be an eighth son, it doesn't specific if it's the only offspring of the father's father that count toward such a wizard's required seven paternal uncles, or if seven brothers who share the same mother are sufficient. Assuming that Nanny Ogg didn't give any of her 15 children a name normally used by the other sex, and assuming that "Dreen" is a female name, Shawn has seven older brothers or half-brothers (Jason, Grame, Nev, Trev, Kev, Wane, and Darron) who share the same Mom, which is enough to make him the potential father of a wizard if he, as per Ogg tradition, fathers a large number of kids.

Rincewind is a much more powerful wizard than he appears to be.
"Many a young wizard has tried to read a grimoire that is too strong for him, and people who've heard the screams have found only his pointy shoes with the classic wisp of smoke coming out of them and a book which is, perhaps, just a little fatter."

- Mort

Rincewind has looked into the Octavo, which contains the most powerful spells in the world, and survived.
 * Yes, but that was because the Octavo sort of knew it will later need him. I think that's even said in canon.
 * It knew it would need him, so it opened all of the locks and let him in. It still wouldn't explain why it chose a complete incompetent who, supposedly, was unable to achieve the same magical skill as a non-magical person, though. On the other hand, at a time when all other magic on the Disc had failed due to a mysterious red star, Rincewind was able to use magic to open the lock on the door to the Octavo's room. The heavily magic-proofed door. And there's nothing there to even suggest that the spell helped, either.
 * Maybe Rincewind had so little magic in him, there was plenty of space for the Octavo spell to fit in. Anyone else would have gone over their 'magic limit' and died horribly.
 * Isn't it sort of stated in the cannon that the reason he is so magicless was that all of his magic was used in containing one of eight, and it seams to me that reading out all eight would leave him changed in some way. So perhaps his insanely convoluted life-glass is not only due to the Lady. And, at least to me, it appears that Rincewind in a manner of speaking also stands at the borders...
 * Where else would you hide powerful magic besides in person completely worthless at magic and where no one would expect to find magic anyway? In him of course.

Uberwald has a citizen named Sucking My Own Blood Diblahh.
Because if it doesn't already it damn well should!
 * Shouldn't it be von Dibbler or somesuch?
 * Schnapper. As Throat's name in the german translations is Treibe-mich-selbst-in-den-Ruin Schnapper, why not have his überwaldean incarnation have that name?
 * Or Bite-Me-Own-Throat Dibbler (carefully pronounced Dib-blah, purveyor of Holier-than-thou Water, silver that turns your skin green, wooden carrots that never go bad, and shallot-flavored wurst of dubious origin), who is (was?) very, very careful to never introduce himself in full to a REAL werewolf or vampire.

Auditors hate elves more than Human Beings
To an Auditor, an Elf is worse than an Human Being. Not because elves are sadistic, but because they make a bigger mess of the world. They warp distortion of the world and act solely in motivation of whatever gives them a little kick of pleasure whatever that may be. The fact that they kill people is not of consequence, as Elves would probably prefer it on the whole if that race of playthings stayed alive. In short, they do more to upset the paperwork than mere men. Indeed, i can imagine that the Dancers in Lancre had an origin story involving a few asteroids being specifically re-directed and a couple of witches being met by floating empty roads which were told by a trio of floating robes that the gateway between the Discworld and the Elves' home dimension was bridged by the disc and what was needed to be done to seal the gate.
 * It would depend if auditors feel Elves are technically part of the same universe (and thus under their juristiction.
 * Jurisdictional issues didn't stop them from invading Roundworld in The Science Of Discworld III, and that's another universe.

Ponder Stibbons is the reincarnation of Ymper Trymon and it's slowly showing
Granted, he may not look like Trymon, but everything else is there: The obsession with organization, the view on magic (and maybe the world in general), and several other things. In the past few books we saw Ponder in his behaviour got weirder and weirder and, to add the final bit of fuel to the fire: Going by the not-that-much-official timeline the good folks over at L-Space figured out, Ponder was born the very same years Trymon died.

Death is the personification of life.
He works in a world of life-energy, life-timers, biographies, afterlives and rebirths. If there really was “some great white crackling thing, like an electric storm in trousers” somewhere, one can only wonder what would be left for him to do.
 * Or maybe Death is just Death and we'll never meet the personification of Life as she is not needed for the stories. Sadly.
 * Alternately, Life is the one who leaves when it's time for Death to take over. Death takes care of all the clinical details, but Life, ah, Life handles all the messy stuff, the stuff that doesn't need an auditor or bookkeeper but just needs someone.
 * If Death gains those properties of personification, would he still be recognizable as Death? The Hogfather doesn't resemble his old incarnation much; the Grim Reaper may be a bit too cultural specific in its definition to make narrative sense. A Death-and-Rebirth equivalent. perhaps some Agatean-equivalent, would look much different...

Susan is (or will become) Neil Gaiman's Death.
She's a pretty young woman who (at least for a while) is Death. It's obvious. Susan says in Hogfather that the longer she spends doing Death-y or immortal things (walking through doors, using, and the like), the closer she gets to actually being Death. Someday the old boy will decide to retire (or something nasty will happen to him; it's bound to happen eventually, as much as we all hate to admit it) and she'll end up taking over. Of course, there's the minor issues of her hair and age being entirely different, but... I think we can work around that.

The wizards aren't allowed to have sex...
...not because of the dangers of the result might be a sourcerer, but because of the OTHER possible results of fathering a child when the genetic material is magical. Even if one is NOT and eight's son's eight's son.
 * For what it is worth, the book that introduced the concept of a sourceror began with describing the seven first sons of a wizard as "as powerful from birth as any wizard in the world". So, if wizards had sons, even if they stopped before getting to the eight, that would drastically increase the population of wizards - and we all know what wizards can do if they aren't careful. Of course, later books seems to have retconned down the whole eight son-eight son business and the severity of the 'not having sex' rule, but this is Wild Mass Guessing.

Failing early Assassin training doesn't automatically get you killed, it just puts you in the "special" class.
Where they teach you all the cliches; wearing all black, announcing yourself before attacking, etc. There are some "Special" Assassins who somehow survive, but they aren't common. More importantly, they take attention off the real ones. Vimes was on the no-no list from the beginning.

Rincewind will preincarnate as himself
Just imagine how fitting it would be, him being forced to relive his life over and over again. Plus Fate seems to have it in for him, so he might have something to do with it.
 * On the other hand it seems the gods DID lose their interest in him when he not-voluntered in Last Hero...

Susan will succeed Death
Think about it; Mort and Ysabelle are dead. So their is only Susan left. And as we saw in Reaper Man it is possible for death to err.. Go.
 * That's what happened to Lobsang.

Most souls dissolve shortly after being guided out of life by Death.
We only see a small moment of time once someone dies and Death leads them elsewhere and then the "camera" pans away. Without a body, the soul temporarily assumes a morphogenic field, but only for as long as the soul can keep believing in their memories. Similar to how "borrowing" a body too long makes one become that thing permanently, not having a body at all eventually has one's mind become what it's inhabiting. Nothing. Or else a distance, vague shadowy echo, like small gods.
 * God-created afterlives are rare. (Om, for example, apparently didn't bother to store the souls of his faithful after dead.) Dead souls tend to focus on keeping themselves intact and do not manifest enough belief to sustain a deity, making it very cost-ineffective. Deities thus prefer living followers. Should one be lucky enough to have a deity who cares enough to set aside a sanctuary, this sanctuary dissolves when a god inevitably dies or becomes a small god.
 * Alternatively, afterlives are fairly common, but aren't maintained by the god; rather, afterlives are maintained by the belief of the living in said afterlife, generally the same set of belief that empowers the associated god in the first place. This explains why it happens (the god doesn't need to expend any energy to do it), and also has the same general problem that the afterlife will eventually fade when there aren't enough living who believe in it anymore.
 * The existence of Hell in Eric would appear to support this. Note that one of the characters encountered there, Lavaeolus, retained his own identity and memories many centuries after his death.
 * Reincarnation has the same issues as Borrowing. Only trained monks can reincarnate and keep any semblance of an previous incarnation after the death of their current selves (as evidenced with how we only see monks remember being other people when they're talking to Death.) Nobody else suddenly remembers their past lives after dying; and only the ultra-rare can maintain an identity while alive. Otherwise, one's soul is completely consumed by their new identity. Usually when Person A reincarnates into Person B; when Person B dies, NOTHING of Person A is recovered. (Unless Monk-trained)
 * Death is not aware of this, as it's not his domain. Neither is he exempt. His very existence will be reabsorbed by Azrael one day; just like how the Death of Rats will one day be reabsorbed into him.

Most gods and Anthropomorphic Personifications will be replaced by ascended humans and hybrids.
This has already started to happen. Nuggan was replaced by the Duchess, Time was replaced by Lobsang.
 * Brutha is going to replace Om.
 * Susan is going to replace Death.
 * Anoia, goddess of misplaced things/Lost Causes; is Genre Savvy enough to see this and has created a human self (Adora) in order to take advantage of the trend.
 * Vimes is going to become the apparently non-existent God of Watchmen.