Enemies both infamous and obscure abound in another archive of the X-Men"s early adventures! Mainstay malefactors like Magneto and the Juggernaut are joined by the thunderous threat of Factor Three! Plus: the first appearances of Banshee and Polaris! Mimic vs. the Super-Adaptoid! Subterranean civil war! The X-Men"s first individualistic uniforms! The return of a Golden Age great... and the death of Professor X!? Guest-starring Spider-Man, Doctor Strange and the Avengers! Featuring Ogre of Thunderbolts fame! Collects X-Men #25-53 & Avengers #53.