Mainframe

A product of Marvel's bold early-'90s mutant explosion, Mainframe made their debut in the pages of X-Men #16 (1993), brought to life by the acclaimed creative team of Fabian Nicieza and Andy Kubert during one of the most kinetic eras in the publisher's history. Over a publishing span stretching all the way to 2019, this character carved out a place in the sprawling Marvel cosmos, sharing panels with heavy-hitters like Nathan Summers and the hard-edged cast that populated the X-Force corner of the universe. Mainframe may not be a household name, but that's precisely the kind of discovery that makes digging through Marvel's deep catalog so rewarding — a Copper/Modern Age figure with genuine longevity and a footnote in some of the most collectible X-Men material of the decade.