The Dark Avengers are a group of supervillains who banded together under the leadership of the influential Norman Osborn, who was also the leader of the Thunderbolts and SHIELD. Osborn created the team to defend America after being appointed the new Head of S.H.I.E.L.D. after an invasion of the Earth by the alien Skrulls. Each of the members took on the identity of one of the Avengers. On their first misison they successfully defended Osborn's ally Doctor Doom from the demon hordes of Morgan Le Fay. They were initially praised by the public as heroes, but soon showed their true colors. This group consists of about 21 supervillains.
Osborn formed an alliance with Loki and led the Dark Avengers in an attack and siege of Asgard. The Dark Avengers disbanded after this war and their final defeat by the real Avengers.
They battled the real Avengers many times throughout their career, as well as the X-Men.
After the invasion of the Earth by the alien Skrulls, Anthony Stark (also known as Iron Man) was ousted from his position as head of S.H.I.E.L.D. He was replaced with Norman Osborn (formerly known as the Green Goblin) due to his work with the Thunderbolts and the fact that he was the one that succeeded in killing the Skrull Queen Veranke. In addition to inheriting S.H.I.E.L.D., which he dismantled and reformed as H.A.M.M.E.R., Norman also inherited control over the Avengers. None of the then current Avengers, barring Ares and Sentry, were willing to work with him however, prompting Norman to form his own Avengers team, consisting mostly of the villains he had worked with in the Thunderbolts. Norman had these villains pose as known heroes, and took the identity of "Iron Patriot" (a blend of the heroic imageries of Captain America and Iron Man) for himself.
The team's first mission was to assisst Doctor Doom in reclaiming control over his homeland. While escorting Doom back to his home country of Latveria, the Dark Avengers came under attack by the evil sorceress Morgan le Fay. Morgan had come to the present to take revenge on Doom, and the Dark Avengers were caught in the middle. Morgan trivilaised their efforts to subdue her with her magic, but Doom and Osborn travelled back in time to Morgan's own time period, and disrupted the ritual that kept her in the present, trapping her in the far past.