It's Always Sunny in Philadelphia

It's Always Sunny in Philadelphia

The cast of "It's Always Sunny in Philadelphia," clockwise from top right: Glenn Howerton (Dennis), Charlie Day (Charlie), Danny DeVito (Frank), Kaitlin Olson (Sweet Dee) and Rob McElhenney (Mac).

Season three of "Sunny" premieres with back-to-back episodes Thursday, Sept. 13 at 10 p.m./9c on FX.