Wolverine is the codename used by the man known only as Logan. He is a mutant and adult member of the X-Men and formerly a member of S.H.I.E.L.D.. Sometime into his membership on the team, it became evident that elements of his past had come back to haunt him, such as Sabretooth and the scientist that had installed the chip in him. Despite this, he still managed to form relationships with the other X-Men, most prominently Shadowcat, and also extending to Rogue, Nightcrawler and even a female clone of himself named X-23.