12 Biggest Unanswered Marvel Movie Mysteries

12. Where Is Red Skull?

Given the well publicised problems with Marvel's movie villains, you'd think they'd be exploiting every opportunity to bring the ones they know worked back - particularly when they aren't actually as dead as they might seem.

At the end of Captain America: The First Avengers, Hugo Weaving's Red Skull is randomly sucked off somewhere mysterious. Since he's never mentioned again, it's safe to assume that Marvel just want us to assume he's dead, even though Kevin Feige has gone on record to say that the manner of his death was chosen specifically "to showcase to people that he could perhaps pop up again sometime."

So where the hell is he? Is he trapped inside the Stone as the lore of the comics would suggest? Is he on the other side of the portal that the Chitauri entered from in The Avengers? Is he trapped between time and space? And most importantly will we get any of those answers in Infinity War and beyond? Just imagine the Avengers standing triumphant over Thanos and breaking the Infinity Gauntlet only to accidentally unleash Red Skull, Ronan and Ultron's robo-spirit.