Which 1991 action sequel revolutionized visual effects with the T-1000, a villain composed of a 'mimetic polyalloy' liquid metal that could shapeshift into other people?

Terminator 2: Judgment Day

Directed by James Cameron, the film was a pioneer in the use of computer-generated imagery for character animation. It flipped the premise of the original movie by casting Arnold Schwarzenegger as a protector rather than an assassin.