X-Men: Endangered Species

In 2008, Marvel released this single-issue prologue bridging the gap between the "Decimation" era and the "Messiah Complex" crossover. Written by Christos Gage with art by Tom Grummett, the story follows the Beast as he exhausts every scientific avenue to reverse the M-Day catastrophe that wiped out most of the mutant population. It's a tense, character-driven spotlight on one of the X-Men's most brilliant minds grappling with desperation and moral compromise. This issue matters as a quiet, crucial setup for the larger mutant-resurrection saga to come.