Adjectiveless X-Men is the fan term for various X-Men series that are simply titled X-Men so-called because... well, there's a lot of X-Men books, and adding "adjectiveless" helps make the distinction. The only exception is the very first series that debuted in 1963, which was originally called The X-Men but was later officially retitled Uncanny X-Men that entire series is commonly referred to as Uncanny X-Men for convenience's sake. The "adjectiveless" nickname was originally applied to the second series to be titled X-Men, which launched in 1991 to run alongside Uncanny X-Men.
When X-Men vol. 2 began, the massive ensemble cast was split evenly between the two central X-Men titles: each title focused on a different field team, with this series featured the "Blue Team" of Cyclops, Wolverine, Rogue, Gambit, Beast, Psylocke and Jubilee (while Uncanny X-Men featured the "Gold Team"). The series notably had comics superstar Jim Lee as artist and co-plotter; the first three issues were scripted by legendary X-Men writer Chris Claremont, who had been writing Uncanny X-Men since 1975. Issue #1 was and still is the best-selling single issue of all time, with over eight million copies sold. After Claremont's departure the series was scripted by John Byrne and then Scott Lobdell then, when Jim Lee left Marvel in 1992 to co-found Image Comics, Fabian Nicieza took over as the new writer. This entire era was notorious for frequent crossovers, not only with other X-Men books but with other series as well, which has made it very difficult to collect in trade.
Soon after the Age of Apocalypse event in 1995, Nicieza left the series and Lobdell (writer of Uncanny) took over the adjectiveless title as well, integrating the two core X-books much closer together. Lobdell was followed by Joe Kelly in 1997, and Alan Davis with Terry Kavanagh in 1999. The line-wide relaunch X-Men: Revolution in 2000 saw Claremont's brief return as writer from issue #100. In 2001, the series was retitled New X-Men from issue #114 for Grant Morrison's cerebral sci-fi run; for tropes relating to that era, see its own page. The 2004 relaunch X-Men: ReLoad saw the series' name revert back to X-Men from issue #157 under new writer Chuck Austen, who carried over the stories and characters he had previously been writing about in Uncanny X-Men. Austen was soon followed as writer by Peter Milligan, and then by Mike Carey.
Following the 2008 crossover event Messiah CompleX, X-Men vol. 2 was permanently retitled to X-Men: Legacy from issue #208. The series initially focused on continuity-heavy stories featuring Professor Xavier, before shifting focus to Rogue from issue #226 onwards. Carey left the series after issue #260 and was replaced by Christos Gage; the series ended with issue #275. Much like how the name Uncanny X-Men is used to refer to that entire series even before its title change, some sources now also refer to the entirety of X-Men vol. 2 (bar the New X-Men era) as X-Men: Legacy, including The Other Wiki.
Meanwhile, a new adjectiveless X-Men title X-Men vol. 3 was launched in 2010, originally written by Victor Gischler and then by Brian Wood. This series focused on the role of the X-Men in the wider Marvel Universe, and featured "guest characters" who usually don't appear in X-books, such as Blade and Daredevil. As part of the Marvel NOW! line-wide relaunch in 2013, this series was canceled at issue #41 and immediately replaced by its successor, X-Men vol. 4 (also written by Wood), which featured an all-female team. Unlike the other main X-books of the time, which either aligned with Cyclops' team of rebel X-Men or with Wolverine's school, this series just featured an X-team in general it became known as "that other X-book" due to being largely influenced by the other X-books. This series crossed over with the other X-titles in the Battle of the Atom Bat Family Crossover in its second story arc, and two of its cast were hijacked by other series. Wood's run was followed by story arcs from Marc Guggenheim and G Willow Wilson. The series was canceled in 2015 at issue #26.
X-Men vol. 5 launched in 2019, written by Jonathan Hickman as the flagship book of the X-Men line of comics under his overall creative direction. It is part of the Dawn of X relaunch. For more on that, see Jonathan Hickman's X-Men. After Hickman ended his volume, a new one, X-Men (2021), was launched, written by Gerry Duggan, but still part of Dawn of X.
Tropes applying to X-Men volume 2:
- Anti-Hero: Bishop, of the '90s Anti-Hero variety when he first appeared, being a police officer from a Bad Future with a fondness for using guns rather than his mutant powers.
- Brainwashed and Crazy: For Claremont's swan-song on his first seventeen year run on X-Men, he brought this trope along one last time, with half the team getting brainwashed into following Magneto.
- Breaking the Fellowship: The pre-Messiah Complex team, thanks to Mystique and Lady Mastermind's betrayal. As Cyclops bluntly points out to Bobby, there is no point pretending that the team even exists when of their members two have turned traitor, one is possessed by Malice (Karima), another is captive (Rogue), and Cannonball is hospitalized thanks to Sinister.
- Chuck Cunningham Syndrome: Peter Milligan's run had Mystique repeatedly trying to set Rogue up with Pulse, a mutant who could deactivate the powers of anyone near him. The very issue Milligan left, Pulse vanished like he had never existed, and was never mentioned again.
- Eyes Always Shut: The series launched in the 1990s, so Youngblood's Disease was common in the early years.
- Eye Scream: Blindfold, in the last issue of "Blinded by the Light", thanks to foreseeing Hope's birth, which makes her start bleeding from underneath her blindfold. All the more alarming because Blindfold doesn't have eyes.
- Foreshadowing: When attacking Cable in issue 200, Gambit asks him if he knows the phrase "two minutes 'till dawn". Several issues later, Cable repeats it to baby Hope.
- It's Personal: Sebastian Shaw, in the Cronus Machine arc of Legacy, which is the only reason he's involved at all. Up until he learnt he was threatened, he had not cared much beyond "vague curiosity".
- Loads and Loads of Characters: So much that the team was split into gold and blue teams.
- Make Way for the New Villains:
- Magneto's death in issue 3 was supposed to be him getting Killed Off for Real, in favor of folk like Fabien Cortez.
- Almost immediately after Claremont left, the Hellions, long-standing rivals to the New Mutants, were slaughtered almost to a man to make the Upstarts look dangerous. This is generally held as one of the most mean-spirited uses of this trope ever.
- My Skull Runneth Over: Rogue, just before Messiah Complex, thanks to an ancient alien weapon that absorbs the minds of anyone it comes near, and has been traveling across galaxies for centuries.
- No Good Deed Goes Unpunished: Sunfire, during "The Blood of Apocalypse", risks his life to crawl back through Apocalypse's base to save Gazer from becoming a Horseman... only to find Gazer is no more, and so Sunfire gets made a horseman himself.
- The Purge: Issue 200 through 204 has the Marauders going around finding anyone with time-travel abilities or knowledge of the future, as part of Sinister's scheme. Blindfold is the only one to get out, thanks to seeing it coming.
- Reforged into a Minion: Happens to Sunfire, Polaris and Gambit during "Blood of Apocalypse", each becoming a Horseman. Gambit actually did so willingly, but he had been planning to turn it against Apocalypse, only for the brainwashing to prove far too strong.
- Sexy Surfacing Shot: In Issue #8, Scott catches sigh of Psylocke rising out of the water in her leotard and starts stuttering. Jean gets extremely jealous.
- The Bus Came Back: Karima Sharpandar returns during Mike Carrey's run, having last been seen in Chris Claremont's Excalibur a few years before.
- Token Evil Teammate: Rogue's team had half its team be token evil folk - Mystique, Sabretooth and Lady Mastermind. It was honestly astounding it took as long as it did for everything to go to crap.
Tropes applying to Volume 3:
- Guest-Star Party Member: Daredevil, Blade, the Future Foundation, Spider-Man, Ghost Rider and War Machine.
- Superman Stays Out of Gotham: The entire point if the series was to avert this and have the X-Men combat threats in the Marvel Universe as a whole.
Tropes applying to Volume 4:
- Back from the Dead: Madelyne Pryor. Downplayed with Selene Gallio, who is instead just reassembled from being dispersed into the atmosphere.
- The Big Guy: Rogue acted as this for the brief time in which she was present. Monet fills her shoes after she left.
- Bumbling Mom: Jubilee isn't a very responsible parent, taking almost every opportunity to ditch Shogo onto someone else, even if those people are in no way qualified to babysit (O5 Iceman and Beast).
- Dating Catwoman: John Sublime returns and gets some Ship Tease with Rachel.
- Evil Counterpart: The Sisterhood of Mutants is one to the book's feature team, being an all-female team and all.
- Mama Bear: The entire team acts as this to Shogo.
- The Smart Guy: Kitty Pryde, who left the team.