Madcap was a somewhat of a villian in the Captain America
comic book. He never fought Captain America, though. Instead, Cap's partner Nomad
fought with Madcap twice.
Madcap was actually a deeply religious man. One day, he and his church group was going on a trip somewhere when their bus collided with a chemical truck. Everyone except Madcap died. The chemicals from the truck made him invulnerable; he feels no pain, and all his wounds heal instantly. This drove him insane, and he adopted the name Madcap. To him, his life is one of irony, since he cannot die, but all his friends and family are dead. He confided his story to Nomad, who Madcap sees neither as a friend nor foe.
In addition to feeling no pain and automatic healing, Madcap's stare can make people go temporarily insane. He wears a harlequin-type outfit, cape, and a purple hat; and he sometimes carries around a pistol that shoots harmless bubbles. People are led to belive that it is his gun that causes the temporary insanity, but it is acutally Madcap's own power.
Madcap has made brief appearances in Daredevil
, and Ghost Rider
(Vol. 3). He also has his own cable access TV show.