Crossbones a ruthless mercenary who has operated as the right-hand man of the Red Skull as well as a member of the Skeleton Crew, Serpent Squad and, surprisingly, Thunderbolts.
Crossbones first appeared during the “Bloodstone Hunt” storyline in the issues of Captain America. Technically, he made a cameo appearance in issue #359, in one panel, as a figure watching from the shadows.
Crossbones (Brock Rumlow) is a fictional supervillain appearing in American comic books published by Marvel Comics, usually depicted as an adversary of the superhero Captain America. Created by writer Mark Gruenwald and artist Kieron Dwyer, the character first appeared in Captain America #359 (October 1989). Crossbones usually appears as an ally of the Red Skull. He carried out the assassination of Captain America, although a hypnotized Sharon Carter is believed to have fired the fatal shots.