8. The Avengers - Welcome Back The Black Widow
Natasha Romanov is definitely one of Whedon's best female heroines and despite the fact that she comes fourth or fifth in total billing, she really is the central character of The Avengers. She's the one who brings the team together, survives a harrowing event and goes on to do more than her fair share of kicking ass. When we are first reintroduced to the Black Widow in Whedon's film, she is being interrogated in a Russian warehouse by a mob boss, only to flip the tables when she has to go rescue Hawkeye, easily escaping her bonds, beating up everyone in sight and leaving, high heels and phone in hand. Not even breaking a sweat.