Charles Peckham Day (born February 9, 1976) is an American actor, comedian, writer, and producer best known for playing Charlie Kelly on the long-running dark comedy series It's Always Sunny in Philadelphia (2005–present), a role that earned him Critics' Choice and Satellite Award nominations. Born in New York City and raised in Rhode Island, he studied art history at Merrimack College before working odd jobs and taking small TV roles. His big break came when his homemade comedy sketches with friends inspired the pilot for It's Always Sunny, which became the longest-running live-action sitcom in 2021, and he later co-created the Apple TV+ series Mythic Quest (2020–2025) with Rob McElhenney and Megan Ganz. In film, Day has starred in blockbusters like Pacific Rim (2013) and comedies like Horrible Bosses (2011), and is a popular voice actor, notably playing Luigi in The Super Mario Bros. Movie (2023) and its upcoming 2026 sequel. He also made his directorial debut with Fool's Paradise in 2023, rounding out a versatile career that spans television, film, and theater.