The ending of Avengers: Infinity War left fans everywhere asking a lot of tough questions. How many well-loved characters are gone? Is their condition temporary or permanent? And most importantly, who will defeat Thanos now? There are a ton of Avengers 4 fan theories already floating around that try to make sense of the MCU post-snap. Thanos is incredibly strong, and many self-proclaimed nerds are attempting to figure out which characters are capable of defeating the Mad Titan in Avengers: Endgame.
There are plenty of heroes (and villains) in the MCU who have either the power or the cunning to succeed, but which of them is the most motivated? Which of them will have the drive and fortitude to do so? In comic books, there are some characters who have defeated Thanos, but the movies don't always stick very close to the source material. How Avengers 4 will end is anyone's guess.