10 Dumbest Deaths In Comic Book Movies
9. Heimdall - Avengers: Infinity War
How He Dies
In the very opening of Infinity War, the Russos killed off both Heimdall and Loki as a show of strength by Thanos, to show exactly how much business he meant and the truly monumental scale of his threat to the MCU.
Having decimated the Asgardian survivors, Thanos takes unkindly to Heimdall teleporting the Hulk to New York to warn the Avengers about Thanos' impending arrival and stabs him to death. An inelegant method, but it seems to hurt Thor more.
Why It's Dumb
You might think the idiocy here comes down to Heimdall being supposedly All-Seeing and not foreseeing Thanos' attack, but it's even more specific than that. As he proves by sending Hulk to Earth, Heimdall still has the power to conjure dark magic to transport people across the galaxy, so why the hell didn't he just teleport Thanos somewhere else?
That way, the Asgardians can get to Earth to warn everyone themselves and Thanos can't kill either Heimdall or Loki. Or better yet, just teleport him into the middle of the nearest sun.