8. Odin Shows Mercy (Thor)
Okay, Odin's probably not technically a "superhero" in the Marvel Cinematic Universe, but truth be told it was hard to think of ten truly "brainless" actions, so since he is the All-Father and has the Odinpower, I'll cheat. After slaying the Frost Giant Laufey, Odin shows compassion and "adopts" his infant son, whom he raises as Loki...who becomes the bane of Thor's existence. Beyond the people that were more than likely killed when he sent The Destroyer to Earth (more on that later), he's responsible for all the events of The Avengers that led to multiple (implied) deaths when the Chitauri attacked New York. Odin should have realized that he couldn't change Loki's inherent nature even by raising him as one of his own, particularly when he was constantly in the shadow of Thor, who was the apple of Odin's eyesomething that Loki always knew and resented, manifesting itself in megalomaniacal ways. Speaking of the Asgardian clan...