15 Times MCU Heroes Actually Killed
15. Scarlet Witch Committed An Atrocity - Captain America: Civil War
While she initially started as a villain (albeit a misguided, indoctrinated HYDRA guinea pig), Scarlet Witch didn't kill anyone until she changed allegiance to the Avengers. Unfortunately, that wasn't in the service of moral rightness either, as she played a huge part in bringing about the Sokovia Accords by accidentally killing a building's worth of people in Nigeria while trying to save Captain America from Crossbones' suicide bombing.
Obviously, it wasn't intentional, but very few deaths in the MCU have been quite as impactful and quite so tied to the actions of one hero.
Since then, she's redeemed herself somewhat by actually killing for good. In Infinity War, she combined with Black Widow and Okoye to kill Proxima Midnight, landing the "killer blow" by using her powers to throw the villain into the tracks of an oncoming vehicle and smushing her.
Also, she killed Vision for a while, but that was swiftly reversed.