4. Siege
Siege saw Norman Osborn (who is, of course, part of the Amazing Spider-Man franchise) lead his team of Dark Avengers in an attack on Asgard, declaring it as a threat to national security. As a result, a conglomerate of heroes banded together to face Osborn's forces. Sentry, who would need to be brought to the screen in order for this storyline to make it in to the movie world, is the main character in the attack and leads the way, having been manipulated by Osborn in to joining his team. His alter-ego is the Void and during the Siege storyline it managed to take down Asgard by itself, defeating everyone who opposed it including killing an amped, Norn Stone-powered Loki with complete and utter ease. In the comics, the Void was capable of breaking every bone in Hulk's body in seconds, its most basic physical attacks required the combined efforts of Iron Man's, Doctor Strange's (from the Marvel Cinematic Universe) and Invisible Woman's (from the Fox movie universe) shields to keep it at bay and even that was a struggle while the united forces of various groups including the Avengers, the Fantastic Four, the X-Men and heavily armed S.H.I.E.L.D. agents simultaneously attacked it. After that, it battled Thor to the extent that it reverted back to Sentry who, realising what he'd done and knowing he was nigh unkillable unless he chose to die, asked Thor to kill him. Thor reluctantly obliged. Having Osborn as the evil mastermind would bring the Spider-Man universe in to play and, with the threat his team poses requiring numerous groups to oppose it, the Marvel Cinematic Universe's heroes, along with the X-Men and the Fantastic Four, could join forces against them.