Ultimate Avengers (2006)

In the last days of World War II in the European Theatre, Steve Rogers, a U.S. soldier, known as Captain America due to being enhanced with the "Super-Soldier Serum", prevents a missile launch by Nazis, which are soon revealed to be shape-shifting extraterrestrials led by one taking the form of SS officer Herr Kleiser. The missile explosion, however, sends Rogers into a catatonic state, and he falls into the icy waters of the North Atlantic, presumed dead. In the present day, Captain America is found and revived by a S.H.I.E.L.D. team led by General Nick Fury. Bruce Banner and his ex-girlfriend Betty Ross lead a team of government scientists working to recreate the Super-Soldier Serum in order to try and stop the real power that backed the Nazis - the alien Chitauri. Banner thinks the Super-Soldier Serum is the key to him controlling the Hulk, and he secretly uses his blood to try to create a cure, instead of using candidates that had been selected for the rebirth procedure.

A Chitauri attack on a S.H.I.E.L.D. satellite designed to track the Chitauri ships forces Nick Fury's superiors to order the implementation of "Project Avenger", which involves the formation of a team of superhumans. Fury tries to recruit - with mixed success - Giant-Man , Wasp (Giant-Man's wife), Iron Man / Tony Stark , Thor and the Black Widow - and after several setbacks, including a botched mission that led to all but Black Widow walking away from the team, the heroes unite to fight the Chitauri. Although successful, the team must then fight an enraged Hulk, after Banner released his alter ego to aid in the battle against the Chitauri before losing control. The team managed to eventually distract the Hulk long enough for Betty to calm him, and Banner is then incarcerated. The heroes then celebrate their success.