It’s Always Sunny in Philadelphia Season 18 Cast: All the Major Stars Returning to FX’s Hit Comedy

Charlie Day is, of course, back as the wonderfully weird Charlie Kelly in It’s Always Sunny in Philadelphia Season 18. The former co-owner, janitor, and “rat basher” of Paddy's Pub has been making fans laugh since the very first episode, and thankfully, he's not going anywhere. Besides starring, Day also serves as a writer and executive producer on the hit sitcom. This season, Charlie is once again thrown into the gang's ridiculous antics, from tent encampments and workplace automation to conspiracy theories and even a dead woman's inheritance. Just another normal day at Paddy's!

Mac wouldn't miss the madness for anything. Rob Mac (Rob McElhenney) returns as Ronald “Mac” McDonald in It’s Always Sunny in Philadelphia Season 18, bringing back the karate-loving, wildly overconfident co-owner of Paddy's Pub. He's been part of the sitcom since Season 1 and also created, writes, and executive produces the series. This season, Mac is once again caught up in the gang's ridiculous schemes, proving he still hasn't learned a thing.

Obviously, the Gang wouldn't be without Dennis. Glenn Howerton is back as the narcissistic, endlessly self-obsessed Dennis Reynolds in It’s Always Sunny in Philadelphia Season 18. A familiar face since Season 1, he's sticking around for another round of outrageous misadventures at Paddy's Pub. Beyond acting, Howerton also co-created the series and continues to serve as a writer and executive producer. Expect Dennis to be right in the middle of the Gang's latest ridiculous schemes.

Kaitlin Olson is also returning as Deandra “Sweet Dee” Reynolds in It’s Always Sunny in Philadelphia Season 18. A core cast member since Season 1, Dee remains the Gang's only female member and just as hilariously toxic and self-absorbed as everyone else. Whether she's chasing fame, getting dragged into terrible ideas, or throwing insults right back, Dee is sure to bring plenty of laughs in another season of absolute mayhem. And here's a cool off-screen fact: Olson's real-life husband is none other than her co-star Rob Mac.

Saving the best of the Gang for last? Danny DeVito returns as the wildly unpredictable Frank Reynolds in Season 18, and he's already at the center of one of the season's craziest storylines. The official trailer teases Frank preparing to marry his ‘Golden Bachelor’ romance, poultry heiress Samantha (Carol Kane), after their Season 17 love story. It sounds sweet... until you remember this is It's Always Sunny in Philadelphia. Odds are, the trip to the altar won't be anything close to ordinary. So, will Frank actually make it? Fans will have to tune in and find out!