One of her more recent and popular roles is Black Widow in the Marvel/Avengers movies. The one with red hair, dresses in an all black leather biker suit like an assassin, and acts as the sort of voice of reason to help keep the heroes grounded. (like being able to calm down the hulk when he's having one of his fits)
Another role was as the title character in Lucy. The movie where she was conned/forced to be a drug mule and inadvertently got dosed with what she was carrying. This sort of supercharged her mind to superhuman levels, and turned her into a perfect assassin to be able to seek revenge on everyone who did her wrong.