Charles Peckham Day (born February 9, 1976) is an American actor, writer, and producer. He is best known for playing Charlie Kelly on the FX/FXX dark comedy It's Always Sunny in Philadelphia (2005–present), of which he is also a writer and an executive producer. In 2011, he was nominated for a Critics' Choice Television Award and a Satellite Award for the role. Subsequently, he co-created the Apple TV+ comedy Mythic Quest (2020–2025) with Rob Mac and Megan Ganz.