R.E.V.O.L.U.T.I.O.N.
First Appearance: Uncanny X-Men (1st series) #381/X-Men (2nd series) #100
Members: Beast, Bishop, Cable, Cecilia Reyes, Colossus, Gambit, Jean Grey, Moonstar, Professor X, Psylocke, Rogue, Shadowcat, Storm, Thunderbird III, Wolverine
Membership History
Towards the end of the 90’s, the X-titles had undergone a great number of changes to the writing staff and the two main titles effectively functioned as one. That was to change with Uncanny X-Men (1st series) #381 and X-Men (2nd series) #100 when Chris Claremont took up writing duties, after having had an extended period of time away from them. To mark the occasion and give the X-Men a fresh slate for him to work on, every single X-title went through a “six-month gap” where six months had passed in-universe. When the two titles started off, a great number of changes had occurred off-panel in the six months, some of which were explored during future issues and some were left up to the reader’s imagination.
A number of X-Men left the team to pursue other interests, such as Nightcrawler becoming a priest, Archangel taking up more of an active role in Worthington Enterprises and Marrow, whose 
departure was never explicitly expanded upon. Shadowcat left during the six-month gap but re-joined the team again soon after. However, after appearing in the Black Sun mini-series and X-Men (2nd series) #100, she left again.
The team did manage to pick up a brand new member in the form of a new Thunderbird, Neal Shaara, who was the third person to use the codename after John and James Proudstar. First appearing in X-Men (2nd series) #100, his recruitment was expanded upon in X-Men Unlimited (1st series) #27, where it was explained that he had fought against Bastion and his Prime Sentinels months before. His mutant powers had emerged and he had gone to Muir Island to understand them, which is where he ran into the X-Men and was invited to join them.
Other X-Men remained relatively unchanged during the gap, such as Beast, Colossus, Gambit, Rogue, Storm and Wolverine. A few former members returned, such as Jean, who was recovering from the loss of Cyclops, and Psylocke, who had stepped up to active duty as opposed to being a reserve member. Forge had also returned to the X-Men, although he stayed off the active squads and was used as support staff to the various teams as before. Cable had also rejoined the X-Men in honor of his father, Cyclops.
When the titles started off, Uncanny X-Men (1st series) primarily featured Beast, Cable, Gambit, Jean and Storm, whilst X-Men (2nd series) had Colossus, Psylocke, Rogue, Shadowcat, Thunderbird III and Wolverine. Despite leaving the team, Archangel regularly featured in X-Men (2nd series).
As mentioned above, Kitty was the first to leave in X-Men (2nd series) #100, after fighting against the new threat of the Neo. No explanation was given at the time for her departure, as there was supposed to be a mini-series dedicated to her exploits. However, it was never released.
The X-Men gained another new/old member in the form of Moonstar, a former New Mutant and X-Force member, who was now acting as a reserve member to the X-Men when she wasn’t trying to live a normal life. Having debuted in Marvel Graphic Novel #4 along with the other New Mutants, Moonstar officially joined the team in X-Men (1st series) #102 to aid the team against the Neo. After that issue, she rarely operated on the team, instead acting as more of a support staff to them.
Nightcrawler’s life as a priest came to an end when he was mixed up in an attack by the Neo. Joining up with the X-Men to defeat them in X-Men (2nd series) #102, he soon realized that his home was with them and officially rejoined the team.
The Maximum Security story was a line-wide crossover that encompassed numerous titles, both X-Men related and not. For the X-Men, the biggest consequence was that both Bishop and Xavier had finally returned to them after spending months away. Having become lost in the timestream in Bishop: The Last X-Man #1, Bishop finally returned to the present day and rejoined the team in X-Men Unlimited (1st series) #29. Xavier had been absent since taking the group of Skrulls named Cadre K into space to find them a home. He returned to Earth in Maximum Security #3 alongside Cadre K, but chose to stay after the event was over. He was shown as part of the X-Men once again in Uncanny X-Men (1st series) #388, which began the 4-part Dream’s End crossover that ran through the main titles.
The X-Men were dealt some bitter blows during the Dream’s End event when longtime allies Moira MacTaggart and Senator Kelly were both murdered. Moira had been working on a cure for the Legacy virus and she had finally discovered it before her untimely death. Beast managed to recreate the serum but discovered the original host of it would be killed. The X-Men stored the 
serum away until a workaround could be developed, but Colossus had other ideas. Still mourning the loss of his sister from the disease, Colossus snuck into Beast’s lab in Uncanny X-Men (1st series) #390 and injected himself with the serum. He died moments later as it metabolized in his body and released an airborne cure for the Legacy virus.
Having become mixed up with the Neo during X-Men (2nd series) #100-106, Cecilia briefly rejoined the X-Men as she recuperated from the mission. She left the team sometime after Uncanny X-Men (1st series) #390 when she failed to save Colossus’ life.
Whilst many of the others believed Cyclops to be dead, Jean Grey felt otherwise and set off to discover the truth in the X-Men: Search for Cyclops. Teaming up with Cable, the two discovered the Cyclops/Apocalypse hybrid was still alive and that Scott was wrestling for control. With the help of Jean, he was able to purge Apocalypse from his body and mind, and he rejoined the X-Men afterwards.
Another major X-title shakeup was underway, only this time it would split the titles up into three and give each of them distinctive rosters and objectives going forward.
X-Treme X-Men
First Appearance: X-Men (2nd series) #109
Members: Beast, Bishop, Cannonball, Gambit, Lifeguard, Psylocke, Rogue, Sage, Slipstream, Storm, Thunderbird III, Wolverine
Membership History
Many years after her death, the X-Men had come across a number of diaries written by the precognitive Destiny and, when many of the events she wrote about turned out to come true, Storm decided they were too important to ignore. Possessing only one of thirteen volumes, she assembled a team to track the rest down and head-off any potential problems that were depicted in them. Leading the team herself, she recruited Beast, Bishop, Psylocke, Rogue and Thunderbird III, as well as the enigmatic Sage in X-Men (2nd series) #109. This was Sage’s first time working on an active X-team, as it was later explained in X-Treme X-Men (1st series) #3 that Xavier recruited her to spy on the Hellfire Club around the same time he set up the original team. Up until now, the X-Men had only known her as Tessa, Sebastian Shaw’s personal assistant.
The team left the mansion as they needed to separate themselves from the rest of the X-teams in order to work in secret. Their first mission pitted them against the new villain Vargas and the team suffered casualties from the outset. Beast was seriously injured during an altercation with Vargas and when Psylocke came to defend him, she was fatally stabbed in X-Treme X-Men (1st series) #2. With Beast’s injuries being so severe, Storm saw no other option but to remove him from the team in #3 so he could rejoin the main X-Men in New York.
Although they were now down two members, this divergent X-Men team quickly picked some more back up. Gambit, whom Rogue had initially banned from joining the team, became wanted for the murder of an Australian mafia leader. The team met up with him in #5 and he joined them immediately to clear his name. The team ended up protecting the children of the murdered mafia lord, Heather and Davis Cameron, and were shocked to discovered both were mutants. Both first appearing in X-Treme X-Men (1st series) #6, Heather joined the team in #7 as Lifeguard and Davis followed suit in #10 as Slipstream.
The two siblings wouldn’t stick around for long though, as Lifeguard learned that she was actually half-Shi’ar, a revelation that shook both her and her brother to their cores. Slipstream was disgusted by the notion that his sister was an alien and he quit the team in #17. Lifeguard decided to track him down and set things right, so she quit in #19. Thunderbird III had grown romantically involved with Lifeguard by this point and he decided to follow her on her journey, also leaving the X-Men in #19.
Rogue and Gambit would also leave the title around the same time due to some serious injuries obtained by Vargas in #16. After going to the X-Mansion in #19, they also decided to stay there whilst they recuperated. With the team down to just Bishop, Sage and Storm, it was decided Wolverine would join them in #20.
The next new recruit was Cannonball, who asked to join the team in #24. Having rejoined X-Force and then the international group X-Corporation based in Paris, Cannonball hadn’t been a part of the X-Men for a while. However, after a deadly mission in the Channel Tunnel that cost a lot of people their lives, including his teammate Darkstar, he re-evaluated some things. He actively sought out Storm and requested to join the team as he saw the potential for good she was doing.
Wolverine left the team between X-Treme X-Men (1st series) #30-31 for unknown reasons but, 
given that he was also serving on a number of other teams simultaneously, his time was already quite divided. The team gained two former members when Rogue and Gambit came back in #31 to help deal with a group of mutants forcing humans out of their homes in California. Over the rest of the run, the X-Treme X-Men gained a few allies, such as Magma, Shadowcat, Sunspot and Skids, all of whom lent a hand during a given arc but then left the title immediately after. After spending some time away from the X-Men and mourning the death of Colossus, Kitty decides to rejoin the X-Men in #46, which was the last issue of the series. The team would disband soon after that with the various members rejoining the main X-Men group in Westchester.
