Glenn Howerton is an American actor. He started his acting career in the early 2000s. His first notable role was as Corey Howard on That ’80s Show. He next appeared as Dr. Nick Cooper on ER. He got his break after landing the role of Dennis Reynolds on It’s Always Sunny in Philadelphia. He also serves as a writer and a producer on the show. During this period he also appeared in some movies. This includes Must Love Dogs, Serenity, Two Weeks and The Strangers. In the 2000s he had notable roles in the films The Mindy Project, Fargo, and House of Lies.