For those who haven't been following the Avengers universe closely, the question of who actually killed Thanos in Avengers: Endgame can be confusing.
To make matters worse, the film features not one, but two deaths. So let's figure out who actually ended the character's story.
After weeks of searching for the Mad Titan, the surviving Avengers found him on the planet where he was hiding after fulfilling his mad goal. It was there that he was beheaded by Thor, who was furious over the death of his brother Loki.

And no one could have predicted that Thanos could be killed twice in one movie. But Endgame screenwriters Christopher Markus and Stephen McFeely made it possible.
Five years after his death, the Avengers faced a version of Thanos from 2014 who had arrived from his time through synchronized versions of Nebula. However, this Thanos was also defeated when Tony Stark heroically sacrificed himself and snapped the gauntlet with the Infinity Stones.
