3. Odin
Like many Asgardian characters, Odin has died a number of times in the comic books, but finds a way to return to the land of the living whether Thor likes it or not. For example, one recent explanation saw him trapped in limbo, forced to do battle each day with the fiery demon Surtur in order to stop him from returning to wreak havoc on Earth and Midgard. Thor ultimately freed him in need of his father's aid, and an explanation such as this for Odin's departure and eventual return could work really well. That's assuming he is in fact dead of course. Fans don't currently know his whereabouts following the reveal in Thor: The Dark World that Loki was impersonating him, now sitting on the throne of Asgard. At this point, it's not hard to imagine Loki killing Odin, and Anthony Hopkins is the kind of actor it's hard to imagine sticking around in the Marvel Cinematic Universe for another three or four movies. If anything, a triumphant return in Thor: Ragnarok seems most likely, and it would be great to see Hopkins commit to one more instalment to end Odin's journey.