Only a few months after the X-Tinction Agenda crossover, the New Mutants 
title was replaced by X-Force, with Rob Liefeld as "plotter" and 
penciler, and Fabian Nicieza as scripter. New characters Feral (Maria 
Santos) and Shatterstar (Gaveedra 7/Ben Russell) and old character 
Thunderbird (James Proudstar, brother of the original Thunderbird) had 
shown up in the last issues of New Mutants, and helped to form the new 
X-Force team. X-Force was perhaps best summarized by its main character, 
the cyborg Cable. In the Marvel Universe, Cable stood for "taking the 
fight" to the bad guys. In the real world, Cable stood for a change 
towards action and fight-fests, as opposed to the usual slower-paced, 
character-focused issues of Claremont. Young hordes of fans bought 
X-Force with glee, making its first issue the highest shipping comic in 
modern comic history up to that time. Both ideas proved to be spurious. 
Cable ended up "taking the fight" to the villains about as often as the 
X-Men did. 

Debuting within months of X-Force, the new X-Men title (not the same as 
Uncanny X-Men, which had been referred to in abbreviation as X-Men) was 
created to further saturate the X-Men market, and, more importantly, 
saturate the then fan-favorite art of X-Men artist Jim Lee (teamed up 
with by-then co-star Chris Claremont). Five different covers were offered
to fanboys and speculators, who bought multiple copies.

Seeing the figures, the powers-that-be at Marvel decided that current 
fans must be attracted more to art than writing, so they promoted a new 
generation of young artists and emphasized many more merchanizing tie-ins, 
emblazoned with the new art styles, that one could buy to "fit in" with 
the X-Men experience, including t-shirts, posters, pins, and so on.
Unfortunately, the fan-favorite artists were not happy that they got 
little to no return on their work when their art from an Uncanny X-Men 
issue was reprinted on a poster or t-shirt. For these reasons, as well as 
various claims of "creative control," the leading artists of the X-titles 
left Marvel and founded Image Comics where, with complete legal control 
over their new characters, they would make as much money as they could 
over the merchandizing of their own creations. 

Meanwhile, the preferred treatment of the artists over the other creative 
staff caused stress among the creators. Fed up, Chris Claremont finally 
left the titles with X-Men #3 and UXM #281. Claremont and other writers 
(including New Mutants writer Louise Simonson) stated in interviews that 
their main reasons for leaving were annoyance over the amount of editorial 
nit-picking in their stories, and sense of powerlessness given the amount 
of editorial favor for the artists as compared to the writers. 

X-Men continued to sell, and Jim Lee stated in interviews that he had 
plans for the title all the way up to issue #50, but before a year was up 
he was already working at Image. This left Bob Harras in a pickle. He had 
no artistic staff, and many of the writers who had been working for him 
had already left the X-titles. To fill the creative gap on the main titles, 
Harras recruited a bunch of new artists of varying ability, as well as two 
Marvel in-house writers, Scott Lobdell and Fabian Nicieza (Fabian was also 
an editor at Marvel, while Lobdell had a second career as a stand-up comic). 

X-Men became a companion book of Uncanny X-Men. There were supposed to be 
differences in members, purpose, and focus between the two books, but the 
ongoing crossovers and Marvel's scrambling to cover the "X-odus" (as the 
departure of the creative staff on the X-titles was called) made it 
essentially a twice-monthly book coming out under two different titles. 

X-Factor, meanwhile, had undergone yet another change of direction. It
lost the original members to the new X-Men title, and picked up a bunch
of mutants that had been lurking in the background of Marvel stories for
decades as their main characters: Havok, Polaris, Multiple Man (Jamie 
Madrox), Wolfsbane, Strong Guy (Guido Carosella), and Forge. This "new" 
X-Factor was well received due to the excellent work of the new creative 
team of writer Peter David and penciler Larry Stroman. It was cancelled
and rebooted after issue #149.

When the X-Men animated series came out, Marvel, never slow to miss a
potential tie-in, put out the new title X-Men Adventures, which did
adaptations of the cartoon series. Since the cartoon series itself was
adapting three decades of X-stories, long-time X-readers tended to get 
odd feelings of deja vu. It was later joined by the title Adventures of 
the X-Men, which printed original stories based on cartoon continuity. 
Both were later cancelled, as was the cartoon series, and X-Men: The 
Manga" was created, publishing the same stories X-Men Adventures used 
to publish. Plagued by lateness, it too was cancelled.

As part of Marvel's new marketing strategy, the Unlimited series of 
books was brought out. The idea of the Unlimited books was to focus on 
stories that would be more "character-based" than normal Marvel titles, 
whatever that would mean, and would be told in just one oversized issue. 
For a while, the title went to an anthology format, including three 
short stories per issue.

Also around this time, Marvel came out with a group of titles that 
shared a common theme: they were placed about 100 years ahead of 
"normal" Marvel history. Called the 2099 series, they featured a bunch 
of alternative future versions of Marvel standards, including Spider-Man 
2099, Punisher 2099, and X-Men 2099. Aside from reverent mentions of 
some of the older X-Men, however, X-Men 2099 rarely had anything to do 
with the continuity of the "older" titles.  After a few years, it too 
was cancelled.

If nothing else, Marvel has always shown a rather strong interest in 
keeping its old stories available to the public (maybe because it's 
cheaper just reprinting the old stuff). The next X-title to appear was 
in this vein: X-Men: The Early Years, which reprinted the original X-Men 
series, from back in the 60s, while X-Men Classics continued to reprint 
the "new" X-Men stories. It was cancelled after 19 issues. The book was
replaced by Professor Xavier and the X-Men, which retold the early tales
from a more modern viewpoint. It also was cancelled after a few issues.

Eagle-eyed FAQ-readers are no doubt seeing a familiar pattern here.

Various other crossovers and battles took place over the next few years. 
Just after the reshuffling, Bishop appeared from the future, and joined 
the X-Men team. X-Cutioner's Song featured the introduction of Stryfe 
and the Legacy virus, and revealed Cable as Scott and Madelyne's son 
returned from the future and the return of Apocalypse. (It was around 
this time that Scott Summers and Jean Grey finally married.) Fatal 
Attractions featured the death of a de-aged Magik, the return of 
Magneto, and Colossus' choice to defect to Magneto's acolytes. It also 
featured Magneto ripping the adamantium off of Wolverine's bones through 
his skin. Xavier eventually mindwiped Magneto to stop him. It didn't 
stop the Acolytes, though, as yet another crossover (this time between 
Avengers and X-Men) called Blood Ties featured the kidnapping of 
Quicksilver's daughter by Magneto Acolyte and impersonator Fabian 
Cortez. The art was "kewl" and the events were extreme, but something 
was still lacking.

The decision was made to make yet another title to expand on the X-Men 
theme and return to the basic ideas of the old X-Men and the New 
Mutants: teaching young mutants to both fit in the world as well as to 
use their powers. The Phalanx Agenda crossover introduced the new cast 
of young mutants, which eventually became Generation X. Scott Lobdell 
wrote and Chris Bachalo pencilled this new title, which featured Banshee 
and the White Queen (Emma Frost) teaching the younger generation of 
mutants in Frost's Massachussetts Academy, now the "School for Gifted 
Youngsters". Xavier finally changed the original X-mansion school to an 
"Institute for Higher Learning." Generation X featured Jubilee 
(Jubilation Lee), Husk (Paige Guthrie), M (Monet St. Croix), Skin 
(Angelo Espinoza), Synch (Everett Thomas), and Chamber (Jonothon 
Starsmore) as the first students, and they found themselves facing 
Emplate in their first issue. 

In summer 1994, as Generation X was just hitting the stands, the 
greatest crossover of all was planned: the end of the universe!  Age of 
Apocalypse (AOA), and its lead-in, Legion Quest, tied it all together. 
Due to a time-travel glitch, an alternate reality was created. In this 
"World Without Xavier," Apocalypse was in charge, and Magneto led the 
heroic opposition. All of the writers' (and some fans') fantasies came 
true: Cyclops was a villain, Jean Grey and Wolverine were a couple, 
Magneto and Rogue were married with a child, Doug Ramsey wasn't dead, 
and Kitty and Colossus were married, to name a few. All of the comics 
were retitled and renumbered (starting at #1). The casts were scrambled 
as well, with X-Force becoming Gambit and the X-ternals as the most 
extreme example. Through the machinations of all the books, the timeline 
was restored to normal, with four AOA characters remaining in the "real"
timeline: X-Man (Nate Grey), Sugar Man, the AOA version of Beast, and 
Holocaust. Nate Grey got his own title, X-Man, the only AOA title to 
continue past the crossover itself. When AOA ended, numbering of the 
other titles continued where it had left off.

The next mega-crossover was Onslaught.  In that crossover, a psychic 
construction with all of the worst parts of Xavier and Magneto decided 
to try taking over the world.  This crossover was different in that in 
had a greater impact on the rest of the Marvel Universe than it did on 
the X-Men themselves. Onslaught set up the reboots of Iron Man, the 
Fantastic Four, the Avengers, and Captain America, and caused the 
characters' (temporary) removal from the Marvel Universe. Rob Liefeld 
had once again been courted to raise sales on those four titles, even 
though Mark Waid's previous six months of work on Captain America had 
turned the title into a solid seller. After Liefeld, Jim Lee, and others 
finished their runs on the titles (Liefeld's being shorter than the 
planned 12-issue run), the books were restarted with number 1 issues. 
Meanwhile, Waid wrote some issues of the X-Men, adding Cannonball to the 
team, but left soon after. A Magneto stand-in, Joseph, was briefly a 
member, as was Quicksilver (Pietro Maximoff, Magneto's son).

Following Onslaught, the X-Men were on their own during the Operation: 
Zero Tolerance crossover. As "Operation: Zero Tolerance" continued, Bob 
Harras realized that things were not going well in the X-titles. On the 
main front, Uncanny X-Men and X-Men writer Scott Lobdell was trying to 
tank the story because he wanted the X-Men to lose and editor Mark 
Powers refused to let them. At the same time, X-Factor was becoming a 
mess of new characters, and Excalibur was going through writer cramps as 
Warren Ellis left the book. So Harras acted to change things.

The first books to get the big treatment were the X-Men and Uncanny. 
They were given to Joe Kelly and Steven T. Seagle, respectively, who 
shook things up by adding three characters: Marrow (a terrorist), 
Maggott (a South African), and Cecelia Reyes (a doctor). The book went 
in some interesting directions, but their tenure lasted only eight months
since management decided that a new, different direction was in order. 
Listening to complaints about the size of the X-Men team, a decree was 
made that the book should have a team of 7 or 8: Wolverine, Storm, Marrow 
and Rogue would stay on; Excalibur, which was rapidly losing sales, would 
be closed down, and its main three characters--Shadowcat, Nightcrawler 
and Colossus--would return. And then there was Gambit.

After decent sales on Gambit's mini series and letters asking for his 
return after being unceremoniously dumped in the snow in Uncanny X-Men 
#350 (after revealing his part in the Mutant Massacre), a solo book was 
set to spring out of events in one of the down-time issues. Fabian Nicieza 
returned from his editorial stint at Acclaim Comics to begin the writing 
job on the title. (It was eventually cancelled with #26.)

With such upheaval--dissolution of a team book, retrenching on the two 
core titles, Larry Hama leaving Generation X after dismal reception and 
new writer Jay Faerber coming in with new ideas, and John Francis Moore 
setting up X-Force in a new way--Harras turned to the remaining book: 
X-Factor. Writer Howard Mackie and editor Frank Pittarese were asked to 
come up with something radical. The result? X-Factor would halted at 
#149 (after constantly promising a big payoff in issue #150) and Havok 
would go to another universe where the rules were changed. This would 
last for a year, and then Havok would return to take the team in a 
different direction. Harras was ecstatic and he okayed the move. X-
Factor became Mutant X, a twelve issue maxi-series that was received so 
positively, the book was continued. (Unfortunately, the positive start
soon turned negative, and the book was cancelled with #32.)

Back to the core titles. The drastic reduction of the X-Men's numbers, 
combined with the addition of Marrow and the members from the defunct 
Excalibur team, left everyone in a bit of a muddle. The Psi-War soon 
stripped Jean Grey, Psylocke, and Cable of their telepathic powers. (Of 
course, in typical Marvel fashion, the power losses lasted for only a 
short time.) Seagle and Kelly came up with some very interesting plots, 
but the two authors were soon replaced by Alan Davis, who was supposed 
to come on for six issues only but stayed until a "full-time 
replacement" could be found.

Davis was forced to do the "Rage Against the Machine" event immediately 
after his second story arc. The story, leading to the annuals, launched 
the M-Tech line: Warlock, Deathlok and X-51: Machine Man. Sales on the 
three books were dismal. (Although Warlock was the most X-related, and 
the best-written, Marvel held the cancellation on X-51 another month 
thinking it possible to remarket that title as an X-book. Didn't work.)

Xavier was missing around this time, and the X-men went on a search for 
him. Cerebro, who had been taken by Bastion earlier, was rampaging and 
Xavier was hiding from the machine, not able to contact the X-Men. 
During the "Search for Xavier," they found him. Joseph turned out to be 
a copy of Magneto. After the battle with Magneto, Joseph died and Magneto 
was given Genosha by the UN. Then came "The Shattering." Xavier felt 
something was wrong, and dissolved the team. During "The Shattering," the 
members of the teams went off on their own, to recover from the events of 
O:ZT and the like. 

It was during this ebb that Bishop returned home to the mansion and chose 
to go his own separate way as well. Bishop: The Last X-Man #1 began in 
"The Shattering," when he and Storm were alone in the mansion. Before he 
could change his mind, he was whisked away. Bishop:TLXM chronicled the 
tale of Bishop versus the Chronomancer (aka Fitzroy) in an alternate 
future. While Bishop was somehow sucked back into continuity during the 
Twelve storyline, he was whisked back to his own title soon afterward. 
(Bishop returned home again in his title's final issue, #16.)