Twins (1988)

Arnold Schwarzenegger and Danny DeVito are twins. That's the joke, and somehow it's enough to carry an entire movie. In Twins, Arnold plays Julius, a gentle, brilliant, physically perfect man who discovers that his long-lost brother is the street-smart, scheming Vincent. Their completely opposite personalities turn a simple family reunion into a road-trip comedy full of awkward encounters, misunderstandings, and surprising heart. What makes the movie work is Arnold's willingness to play innocent and sweet instead of intimidating. You get to see a side of him that Predator and Commando never touch. Is Twins his greatest movie? Action fans will probably laugh at the suggestion, but comedy fans have a real argument. Sometimes the best Arnold isn't the one holding a gun.