Charles Peckham Day, born February 9, 1976, is an American actor, writer and producer. He is best known for playing Charlie Kelly on the sitcom It’s Always Sunny in Philadelphia (2005–present), for which he was nominated for a Critics’ Choice Television Award and a Satellite Award in 2011. In 2020, he co-created the Apple TV+ comedy series Mythic Quest alongside Rob McElhenney and Megan Ganz. In film, he is known for his role as Dale in the films Horrible Bosses (2011) and its 2014 sequel, as well as for his roles in Monsters University (2013), Pacific Rim (2013), The Lego Movie (2014), Fist Fight (2017), Pacific Rim: Uprising (2018), and The Lego Movie 2: The Second Part (2019). From 2018 to 2019, Day was the executive producer on the Fox comedy The Cool Kids.
Besides playing Charlie Kelly on the hit FX television series It’s Always Sunny in Philadelphia, he is also one of the show’s executive producers and one of its writers, along with Rob McElhenney and Glenn Howerton. Other starring roles on the show are played by Kaitlin Olson and Danny DeVito.
Day is married to actress Mary Elizabeth Ellis. They met in 2001 and were dating in 2004 when they co-starred as incestuous siblings on Reno 911!.