Cross-Through

There is a vast universe with multiple series taking place in different places/time periods/whatever, and a Cross Through is a Story Arc that starts in one of these series and cycles through several self-contained series (alternating between them), affecting each one, usually with one recurring element or character appearing in all parts. Compare with Shared Universe and Crossover.

The trope's name was coined by comic writer John Jackson Miller for Star Wars: Vector, which is an example.

Compare the Crisis Crossover (a step up in terms of interconnectedness) and the Red Skies Crossover (a nice big step down.)

Comic Books

 * Star Wars: Vector is a Cross Through of four Star Wars comic book series that take place during different time periods, featuring an Artifact of Doom of an ancient Sith Lord that carries a plague of Rakghouls. The plot starts in Knights of the Old Republic (the year 3,963 Before the Battle of Yavin [the original film]), then cycles through Dark Times (19-18 BBY), Rebellion (1-2 ABY), and ends in Star Wars Legacy (137 ABY).
 * The Star Wars books Legacy of the Jedi and Secrets of the Jedi are also apparently this according to their descriptions.
 * The book Rogue Planet takes place in the prequel era prior to the Clone Wars, but it directly ties into the New Jedi Order series, concurrently-published but set generations later.
 * Millennium Falcon is one of these, following the Falcon's history through the Clone Wars up to Han's ownership of it. And it works well.
 * Grant Morrison's Seven Soldiers was this; with seven heroes all individually fighting the same threat. This was in fact enforced by the bad guys, who targetted seven-member enemy teams; if the heroes were to succeed they couldn't meet each other.
 * The Fall of the Mutants storyline in the X-Men comics in the mid-80s. The three titles involved don't directly cross into each other (The New Mutants were the only ones who even knew what the other two teams were up to). Instead, the books are a crossover in the thematic sense of loss and rebuilding: the X-Men's deaths and resurrection, Angel from X-Factor becoming Archangel, the New Mutants losing one of their own and becoming full superheroes, and the subsequent formation of Excalibur.
 * IDW's comic book event Infestation, in which an attempt by IDW's own Covert Vampiric Operations to contain an interdimensional breach of hive minded zombies from the Zombies vs. Robots universe goes awry, allowing the zombies to infest IDW's Transformers Generation 1 universe, the Star Trek Expanded Universe (circa the original series), G.I. Joe and Ghostbusters, attempting to bolster their strength by assimilating the four worlds' technologies. Also qualifies as a Crisis Crossover for some of the series involved, with the Transformers segment having a Transformer be Put on a Bus and leading right into the "Heart of Darkness" miniseries, itself a lead-up to the "Chaos" Story Arc, and CVO seeing a major status quo change at the end.
 * It did well enough that they are in fact doing a sequel for the series, this one starring the Elder Gods in place of Zombies, and Transformers: Hearts of Steel (A Victorian era Steampunk Elseworld), Teenage Mutant Ninja Turtles and the Dungeons and Dragons Eberron campaign in place of Transformers G1, Star Trek and Ghostbusters (CVO and G.I. Joe return for a second round).
 * They're also doing a smaller-scale Assimilation2 crossthrough between various periods of the Doctor Who and Star Trek universes, with different Doctor-companion teams meeting different Trek regular casts to fight a cross-time Borg-Cybermen team-up.
 * Brightest Day wound up being this; all the storylines came out of Blackest Night and many were unified under "people resurrected by the White Entity for a specific task", but each series involved was pretty much self-contained with little overlap.
 * DC Comics 90s crossovers like Underworld Unleashed and Day of Judgement were Crisis Crossovers, but some of the secondary books were more Cross Throughs, with characters fighting over-powered villains/ghosts and demons without ever getting involved in the main story, or even learning what was actually going on.
 * Night of the Owls, a Bat-family storyline launching just after the New 52. The idea is that a cadre of rich, influential people have been ruling Gotham ever since its creation. Batman draws their attention by stopping an assassination, finding them, beating their assassin, and escaping from their clutches. In response, they raise an army of quasi-immortal, near super-powered assassins to strike at Batman and everyone associated with him. Every single Bat-family book faces off against a different assassin during the event.

Film

 * SHIELD Agent Phil Coulson seems to be working his way through the Marvel Cinematic Universe one film at a time as the Hero of Another Story.
 * This is basically the plot of Star Trek Generations, where Kirk falls into the Nexus and Picard meets him there, with a 78-year long mystery about Kirk's fate in between.

Literature

 * There were several series of Star Trek books that did this, with the crews of the original series, TNG, Deep Space Nine and Voyager all facing the same villains.
 * Invasion was the first, with the Furies making their first strike in 2267 (TOS), returning in 2369 (TNG), the enemy that originally drove them out of the Alpha Quadrant returning in 2371 (Deep Space Nine), and their final defeat occurring in the Delta Quadrant the same year (Voyager).
 * Day Of Honor, which culminated in the Star Trek Voyager episode of the same name.
 * The Captain's Table, a bar from another dimension that only admits captains. Originally six novels, featuring Kirk and Sulu, Picard, Sisko, Janeway, Calhoun, and Pike; a later book, Tales from the Captain's Table, turned this into short story format with more captains (including Riker of the Titan, Picard in his Stargazer days, Chakotay of the Voyager post-ending, Klag of the Gorkon (a decade after the exchange program with Riker), Colonel Kira of Deep Space Nine (whose Bajoran military rank is a Captain equivalent), Captain Archer, Demora Sulu 40 years after Generations, Captain David Gold of the Starfleet Corps of Engineers e-Book series, and Shelby a decade after "Best of Both Worlds" (and from the New Frontier timeline)).
 * Double Helix, in which the "villain" was a virulent disease, featured a mix 'n' match approach, with characters not necessarily appearing in the time period most associated with them: 2364 (Next Gen Season 1); 2366 (Next Gen Season 3/Deep Space Nine during the Occupation); 2369 (very old Spock and McCoy); 2371 (the Maquis: Tom Riker prior to Deep Space Nine Season 3/future Voyager characters); 2375 (Movie-era Next Gen/New Frontier); and 2350 (Prequel: Stargazer [Picard's first command]/Ensign Tuvok).
 * Gateways, wherein the Iconian gateways spring to life again, with disastrous results. Gives the interesting hook of an opening real-time holoconference between many of the principles.
 * The Brave and the Bold was a series of novels in which all four crews had to deal with one of four legendary artifacts - with a framing story in which Jonathan Archer (whose first season was still in production) was the first human to hear the legend! Also, much like the DC Comic of the same name (which also gave rise to Batman the Brave And The Bold), each crew was paired with a lesser-known crew from their timeline (Kirk with Commodore Decker and the Constellation from "The Doomsday Machine", DS9 with the Odyssey crew from "The Jem'Hadar"; Voyager with Captain DeSoto and the Hood, Riker's post prior to the Enterprise (and Chakotay's Maquis cell teaming up with Cal Hudson's Maquis cell), and the Next Gen crew teaming with Captain Klag from the Gorkon, a decade after the exchange program with Riker).
 * The concept is also used in the Doctor Who Expanded Universe.
 * Blood Harvest, a New Adventures novel where the Seventh Doctor fights vampires in 1930s Chicago and on Gallifrey, led into the very first Missing Adventure, Goth Opera by Paul Cornell, which had the Fifth Doctor fighting vampires in 1990s Manchester, as a fairly obvious ploy to get new readers interested in the Missing Adventures books. (A short comic in a Doctor Who Annual by Paul Cornell also led into Goth Opera.)
 * The later Missing Adventure Cold Fusion by Lance Parkin is a Fifth Doctor novel that also features the Seventh Doctor, and fit into an ongoing New Adventures Story Arc which had, in real world terms, actually concluded some time ago. However in terms of the Seventh Doctor's timeline it fit into between two of the books in that Story Arc.
 * BBC Books Past Doctor Adventures had a Story Arc in which the companions of various Doctors were seemingly killed in Timey-Wimey Ball situations. This tied into the "Sabbath" arc in the Eighth Doctor Adventures. One of these PDAs, Wolfsbane, also featured the Eighth Doctor during the EDAs' "amnesia" arc.

Live-Action TV

 * Salem of Sabrina the Teenage Witch had eaten a time ball and traveled through the other three shows airing on TGIF at the time: Boy Meets World, Teen Angel, and You Wish.
 * Disney Channel did one of this in regards to their SitComs: the main characters of Cory in The House, The Suite Life of Zack and Cody, and Hannah Montana saw a wishing star on the sky and made a wish (which came true and the episodes are Be Careful What You Wish For plots).

Newspaper Comics

 * Disney Adventures once serialized a five-issue story called "The Legend of the Chaos God" (no relation to Warhammer 40000), involving an Artifact of Doom containing a Sealed Evil in a Can; the comics cycled through more or less the entire Disney Afternoon lineup, starting in Tale Spin and continuing decades down the timeline in Chip 'n Dale Rescue Rangers, Goof Troop, DuckTales, and finally Darkwing Duck (which, despite all being in the modern day, never directly crossed each other aside from Scrooge phoning Darkwing to warn him of the threat),.

Video Games

 * One of the latest Star Trek games, Star Trek: Legacy, does this.

Western Animation

 * A two-part episode of Justice League had Batman, Wonder Woman, and Green Lantern chasing a Mad Scientist through time and joining forces first with the Heroes of the Old West, and later with Future Batman, Old Static, and Warhawk (the son of Green Lantern and Hawkgirl).
 * When the USA Network was carrying Saturday morning cartoons, they had one day devoted to a storyline centered around an original character, the Warrior King, wandering around each show's universe in search of a powerful MacGuffin. The specific episodes he appears in are, in chronological order, "The Warrior King" (Street Fighter), and "Endgame" (The Savage Dragon, the only series out of the four to be based on a comic book series rather than a video game), "Resurrection" (Mortal Kombat Defenders of the Realm, focusing solely on the MacGuffin; the Warrior King makes only a cameo as a shadow at the end, leaving many Mortal Kombat fans unaware of the crossthrough baffled) and "Recreation" (Wing Commander Academy).
 * Cartoon Network ran an event called "Cartoon Network Invaded", which involved cheese-craving aliens from the moon that turn into werewolves. The shows involved were Foster's Home for Imaginary Friends, Ed, Edd 'n' Eddy, My Gym Partner's a Monkey, Camp Lazlo and The Grim Adventures of Billy and Mandy, with a few cameos from uninvolved Cartoon Network shows thrown in for good measure. The crossover ended with the aliens concluding that the Earthlings were smarter than they thought and proceed to suck out the intelligence of their five abducted characters. Unfortunately for them, they turn out to be five of the dumbest characters from each of the shows (Cheese, Ed, Slips Python, Skip the dung beetle, and Fred Fredburger). All five of these shows have alternate endings that sever their connections to the event; for example, instead of the brain-sucking scene described above, the Billy and Mandy episode ended with a Crossover Punchline with Codename: Kids Next Door.
 * In 2011, a hurricane storyline ran across Seth MacFarlane's three shows: The Cleveland Show, Family Guy and American Dad. Each episode of the night featured its main cast trapped in their homes due to a violent hurricane.