X-Men #125 1979 Marvel Comics VG/FN Comic Book Cameo Mutant X aka Proteus

This newsstand edition issue heralds the dramatic return of Phoenix, amidst mysterious events unfolding on Muir Island. The story features the pivotal first appearance of the character known as Mutant X, also identified as Proteus, promising significant new developments for the mutant universe. A classic storyline unfolds with profound implications.