Charles Peckham "Charlie" Day (born February 9, 1976) is an American actor, musician, producer, comedian, and screenwriter. He is best known for playing Charlie Kelly on It's Always Sunny in Philadelphia, and for his roles in the films Horrible Bosses (2011), Monsters University (2013), Pacific Rim (2013), The Lego Movie (2014), and Horrible Bosses 2 (2014).