20 Mind-Blowing Celebrity Cameos In 'It's Always Sunny' That Fans Still Talk About

Season 13, Episode 1 — "The Gang Makes Paddy's Great Again"

At the end of Season 12, Dennis is seemingly written off the show, and thus, Season 13 opens with Mindy Kaling's Cindy serving as the replacement member of the gang. The whole move, however, was a bit of a bait-and-switch, with Dennis returning at the end of the Season 13 premiere and the gang mocking Cindy until she storms off. Kaling's casting, however, did fool some fans into thinking that, as with other sitcoms like The Office or Two and a Half Men, Always Sunny had replaced a cast member so late in the run.