Sigourney Weaver, Aliens
In the first Alien, Weaver's Ripley was an unlikely hero. By the sequel, she was a battle-scarred cynic and part of the fun of Aliens is watching her hold her steely resolve while a squad of space-cowboy badasses get taken down one by one. When the six-foot-tall Weaver hops into the Power Loader and attacks the alien Queen with the immortal cry ''Get away from her, you bitch!'' you know she means business.