Glenn Franklin Howerton III is an American actor, writer, producer and podcaster. He is best known for playing Dennis Reynolds on the long-running sitcom It's Always Sunny in Philadelphia (2005–present) on FX/FXX, a series he developed with creator Rob McElhenney, and on which he serves as an executive producer and writer. Since November 2021, he has co-hosted The Always Sunny Podcast with his fellow co-creators McElhenney and Charlie Day.