Watch It's Always Sunny in Philadelphia series free. An American television sitcom that stars Glenn Howerton, Rob McElhenney, Charlie Day, Kaitlin Olson, and Danny DeVito. The series follows the lives of "The Gang", a group of five depraved underachievers: twins Dennis and Deandra "Sweet Dee" Reynolds, their friends Charlie Kelly and Mac, and Frank Reynolds, Dennis and Dee's adoptive father, who runs Paddy's Pub, a run-down bar in South Philadelphia. Recently it was renewed for the 9th season and will be airing on FXX network.