MCU: 10 Marvel Characters Who Will Definitely Die In Phase 3
8. Thor
Why He Has To Die
Thor definitely won't die permanently in Thor: Ragnarok, even if he does sort of die and end up in Hel to defeat Asgard's new enemy Hela, but there is a good chance that he will be one of the major casualties when Thanos uses the Infinity Gauntlet. That would fit the fact that Chris Hemsworth's contract is set to run out after Avengers 4. Plus, there's no getting around the fact that he's basically the most expendable of all of the Avengers' most powerful characters.
And power is important: you have to assume that Thanos will take down the heroes that he sees as most threatening to him in his initial cull. You don't get much more dangerous than a God with the power to command lightning.
When It'll Happen
Avengers: Infinity War. Depending on how Thor: Ragnarok performs, there may be a reprise for the character (even with a different actor to follow a regeneration of sorts), but expect Hemsworth's contract to not be renewed.
How He'll Die
At the snap of Thanos' mighty fingers, probably.