Avengers: Infinity War - 10 Surprise Cameos That Could Still Happen

4. Adam Warlock

Adam Warlock is already gearing up for a big role in the next Guardians of the Galaxy film, but - considering how big a role he had to play in beating Thanos in the comics - it wouldn't be too far out to have him appear in Infinity War.

Granted, it's possible that James Gunn is setting up the character to debut as a villain initially, before shifting him onto the heroic side of things later on, but it's still a possibility that Warlock will arrive to save the day in the third Avengers film, if not him, then another cosmic analogue in his stead.

In the actual Infinity Gauntlet comic, Warlock is the one who leads the surviving Avengers back in time in a last-ditch effort to take on Thanos once and for all. It yields... mixed results, but there's no denying the character's importance in the source that's inspired the biggest Marvel movie yet.