Fantastic Four vs. X-Men (1987)

Fantastic Four vs. the X-Men is a four-issue comic book limited series published by Marvel Comics in 1987. Written by longtime Uncanny X-Men writer Chris Claremont, pencilled by Jon Bogdanove, and inked by Terry Austin, the series revolves around the quest to find an effective medical treatment for the dying X-Man, Kitty Pryde. Along the way, the Fantastic Four and the X-Men come into conflict with each other, and what appears to be a sinister secret regarding the Fantastic Four's origin comes to light.

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Fantastic Four vs. X-Men #2

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Claremont - Bogdanove - Austin - Oliver - Orzechowski - Nocenti - Daley - Shooter Part 2 of 4 "Truths & Consequences more info

Fantastic Four vs. X-Men #4

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Claremont - Bogdanove - Austin - Oliver - Orzechowski - Nocenti - Shooter Part 4 of 4 "A Matter of Faith" more info