x-men History: 1980.

 1980s ERA: 

The 1980s began with the comic's best-known story arc, the Dark Phoenix Saga, which saw Phoenix manipulated by the illusionist Mastermind and becoming corrupted with an overwhelming lust for power and destruction as the evil Dark Phoenix. Other important storylines included Days of Future Past, the saga of Deathbird and the Brood, the discovery of the Morlocks, the invasion of the Dire Wraiths and The Trial of Magneto, as well as X-Men: God Loves, Man Kills, the partial inspiration for the 2003 movie X2: X-Men United.
By the early 1980s, X-Men was Marvel's top-selling comic title. The growing popularity of Uncanny X-Men and the rise of comic book specialty stores led to the introduction of a number of ongoing spin-off series nicknamed "X-Books." The first of these was The New Mutants, soon followed by Alpha Flight, X-Factor, Excalibur, and a solo Wolverine title. This plethora of X-Men-related titles led to the rise of crossovers (sometimes called "X-Overs"); story lines which would overlap into several X-Books. Notable crossovers of the time included the Mutant Massacre, Fall of the Mutants, and Inferno.

Throughout the decade, Uncanny X-Men was written solely by Chris Claremont, and illustrated for long runs by John Byrne, Dave Cockrum, Paul Smith, John Romita, Jr., and Marc Silvestri. Additions to the X-Men during this time were Kitty Pryde/Shadowcat, Dazzler, Forge, Longshot, Psylocke, Rogue, Rachel Summers/Phoenix, and Jubilee. In a controversial move, Professor X relocated to outer space to be with Lilandra, Majestrix of the Shi'ar Empire, in 1986. Magneto then joined the X-Men in Xavier's place and became the director of the New Mutants. This period also included the emergence of the Hellfire Club, the arrival of the mysterious Madelyne Pryor, and the villains Apocalypse, Mister Sinister, Mojo, and Sabretooth.