Ben 10/YMMV

"Ghostfreak: Ben's not here anymore."
 * And the Fandom Rejoiced: Cartoon Network has announced a new TV-Movie based on this installment of the franchise will air in 2012. Though some may be wary of Destroy All Aliens being CGI animation instead of traditional, the movie certainly wins points for bringing back the original cast to reprise their respective roles and being written by one of the writers from the original series, Marty Isenberg.
 * Canon Sue: Some think Gwen is one, others don't, and others think it varies from episode to episode.
 * Complete Monster: This series has a total of four.
 * Vilgax, a villain who destroyed Tetrax's homeworld, was about to cut Ben's arm off just to get the Omnitrix off (in "Gwen 10", when Gwen asked if they couldn't just slip the watch off, Vilgax responds "And what fun would that be?", and indeed, there is a much easier way.). Among other horrendous deeds.
 * Ghostfreak. The type of guy who will possess a young girl and threaten to make her jump off a roof to her death if her cousin doesn't comply with his wishes. Or cover the world in darkness, which causes everyone on the planet to horrifically mutate.
 * Zombozo, a zombie vampire clown who consumes laughter (draining them of positive energy, apparently), this doesn't sound so bad, but then he kidnaps Gwen draining her until she's pretty much almost a withered husk, and given that he's so casual about it, he's probably done it before, and if you think of it a few other ways, there's a very frightening subtext in there. Incidentally, he was killed by the abovementioned Ghostfreak.
 * Draco in Leather Pants: Kevin 11, of course. Charmcaster gets some as well.
 * Ear Worm: The theme song.
 * Ensemble Darkhorse: Lucky Girl, who is ironically one of the leads in disguise. Her nemesis Charmcaster qualifies on the villain side of things.
 * Naturally, some of Ben's aliens are more popular than others, but the one who takes the cake (from the original series, at least) is Heatblast. He's enough of a dark horse than a Ultimate Alien DVD was titled the Return of Heatblast.
 * XLR8 is also pretty popular, which makes it extra baffling that they went and made Fasttrack.
 * Ghostfreak, mainly because of his Face Heel Turn.
 * Grandpa Max, as detailed in the Just Here for Godzilla entry, even moreso as of the newer series' when he's not a main character anymore.
 * Evil Is Cool: Vilgax and Kevin.
 * Evil Is Sexy: Charmcaster.
 * Rojo, the Circus Freaks, and maybe even Dr. Animo are also this in a Creepy Sexy sort of way.
 * First Installment Wins: While the other two series have their fanbases, many fans are very loyal to the first series. That it's the only one the actual creators worked on helps matters.
 * Foe Yay: Ben and Kevin, who have been chained to each other for an episode, and Gwen and Charmcaster, who spent a good part of one episode inside each other.
 * Fridge Logic: So, if Ben was so desperate to unlock the secrets of the Omnitrix, why didn't he just use Grey Matter's intelligence to do so?
 * Germans Love David Hasselhoff: Gwen is apparently popular enough in Southeast Asia that Cartoon Network Asia gave her a website and a good amount of merchandise.
 * The Franchise is also very popular in Denmark, where many stores hold entire sections of Ben 10 merchandise.
 * Hilarious in Hindsight:
 * Remember that ending in Gwen 10 where the Omnitrix ultimately ended up on Grandpa Max? Several episodes later, some alien named Xylene, a person from Max's past, revealed that the Omnitrix was originally for Max. But thanks to the fact that Ben's DNA was close to his, and Ben was the one who discovered it, it ended up on him.
 * In the end of "Kevin 11", Ben offers Kevin to join him and become allies. Sound familiar?
 * I Knew It!: Some guessed that Ghostfreak would turn evil when they found out the Monster of the Week was an Ectonurite in "Ghostfreaked Out", despite some sources saying that it was a completely separate Ectonurite. When the episode aired, the truth became apparent after a nightmare detailing Ghostfreak telling Ben to let him out of the watch, and then subsequently escaping the watch after dealing with Zombozo's unemployed henchmen.
 * Just Here for Godzilla: Some people just watched the show to see Grandpa Max be completely awesome.
 * Two members of Man of Action themselves, at a convention interview, jokingly stated that Grandpa Max is the obvious REAL star of the show.
 * Moral Event Horizon: Vilgax destroys the planet where all of Tetrax's race lives, killing hundreds of innocent lives for no reason other than to test his brand new toy.
 * And Ghostfreak wanted to plunge Earth into darkness, the result of which is shown to be horrifying mutations of all living things.
 * Also note, that was just a side effect of his plan that he didn't even care about.
 * Zombozo gets his by kidnapping a 10 year old girl and draining her of her energy until she's nothing but a shrivaled husk of her former self, speaking of it so lightly that it's implied it's not the first time.
 * Older Than They Think: There really was a secret organization called the Plumbers - Richard Nixon's private police who did the illegal surveillance of the Watergate hotel.
 * Playing Against Type: Richard Steven Horvitz as Grey Matter. The little alien is certainly more subdued (and a heck of a lot smarter) than a few of Horvitz's other well-known roles.
 * The Producer Thinks of Everything: One of the first line readings for the role of Ghostfreak?


 * Relationship Writing Fumble: Ben and Gwen, in an almost reverse case of the usual trope. The writers PROBABLY viewed them as just bickering, if still loving, cousins (and nothing else), and tried to write them as such. To most of the rest of us...
 * This actually created a Periphery Demographic all by itself. Older viewers initially hated the show, partially because of the flat, immature, two dimensional characters. The instant they decided Ben and Gwen had crushes on each other, the characters gained two or three levels of depth, skyrocketing it to the top of a lot of teen's lists.
 * Seasonal Rot: The third season is generally considered the weakest due to less impressive episodes and overall story arc than the other seasons have.
 * They Changed It, Now It Sucks: Race Against Time. Dear lordy, Race Against Time. Loyal fans were NOT happy when they realized the aliens were not voiced by the original voice actors.
 * Visual Effects of Awesome: "Destroy All Aliens" has particularly impressive CGI effects, with the Galvanic Mechamorph's fluidity being especially noticeable.