1963: X-Men #1 published featuring initial roster of Cyclops, Marvel Girl, Iceman, Angel and a non-furry Beast, led by Professor X pitted against Magneto
1970: With sales in the toilet, Uncanny X-Men series reverts to reprinting old X-Men stories with issue #67. Predictably, sales get worse.
1974: Wolverine debuts in Incredible Hulk #181 wearing a silly costume with whiskers, designed to make him look more like an actual wolverine.
1975: Giant-Sized X-Men #1 debuts new international X-Men: Colossus, Wolverine, Storm, Thunderbird & Nightcrawler. New stories begin again in Uncanny X-Men #94 after five years of reprints.
1980: Uncanny X-Men #129 begins the Dark Phoenix Saga, regarded by comics nerds as one of the finest X-Men stories ever published.
1980: Jean Grey dies in Uncanny X-Men #137.
1986: Jean Grey returns in Fantastic Four #286, found in a cocoon on the ocean floor by the Avengers. Turned out it wasn't really her that died before.
1991: X-Men #1 debuts, selling over a million copies and boasting nearly a dozen different covers with the same story! Collectors buy them all, are astonished when nobody else wants several copies of the same book.
1992: Kickass X-Men animated series debuts on FOX, featuring folks like Cyclops, Jean Grey, Beast, Wolverine, Jubilee & Storm.
1993: X-Men #25, the final chapter of the Fatal Attractions crossover, features Magneto tearing the metal from Wolverine's skeleton and Professor X retaliating by mind-wiping him, beginning tons of bad Wolverine stories and the massive Onslaught crossover spanning 1995 & 1996. Also represents period where there were far too many X-Men spin-off series, eventually resulting in sales going into the toilet again and nearly half of the books being cancelled.
1999: Wolverine gets his metal skeleton back in build-up to another massive crossover. Stories immediately get better.
2000: X-Men released in theatres, grossing $54 million over the opening weekend and nearly $300 million worldwide.
2000: X-Men: Evolution animated series debuts on The WB featuring a younger set of characters more in line with the movie cast.
2001: Colossus dies in Uncanny X-Men #390.
2001: Superstar writer Grant Morrison begins run with New X-Men #114, capitalizing on movie buzz with…wait for it…good stories. Afterwards many writers completely ignore or contradict key story elements (including the deaths of Jean Grey and Magneto). Morrison leaves the company for rival DC Comics, but we're sure that was unrelated.
2002: X2: X-Men United released in theatres, grossing a massive $85 million over the opening weekend and over $400 million worldwide.
2004: Jean Grey dies, again, in New X-Men #150. She's brought back several months later, only to be killed off again.
2004: Astonishing X-Men #1 debuts from Buffy creator Joss Whedon and award-winning artist John Cassaday. The book immediately becomes a huge hit (winning several awards), but is dogged by constant lateness due to Whedon's filming schedule on Serenity and Cassaday's super-detailed artwork.
2004: Colossus returns in Astonishing X-Men #5. Turned out it wasn't him that died before.
2005: House of M crossover cuts down mutant population from several million to slightly over 200 by de-powering popular characters like Professor X & Magneto, less popular characters like Iceman, Quicksilver & Jubilee, and dozens of characters nobody cared about.