MCU: The Worst Thing EVERY Avenger Has Done

Natasha Romanoff may not possess any super-powers, but she's proven time and again that she doesn't need them, as she is perhaps the most efficient of all the heroes.

An infiltrator and hand-to-hand combat expert, she's equipped to handle all kinds of situations that present themselves to her and her fellow Avengers - and she quickly adapted for those that she wasn't - but all of those skills allude to a time when she was anything but a hero.

Black Widow's past is perhaps the MCU's most mysterious aspect as it's rarely talked about and yet constantly alluded to, making us all the more excited to see Natasha's solo film whenever it hits theaters. However, the reason it isn't talked about that much is deliberate, as Natasha was a trained spy and assassin known for committing unspeakable acts for the academy known as the Red Room.

We don't know the full extent of what she did, but we know it's bad enough to make this formidable warrior feel regret and heartache every time she referred to her past. And given all that she went through with The Avengers, it's safe to say she removed some of that red from her ledger.