It's Friday the 13th, or Sunny the 13th Season, as It's Always Sunny in Philadelphia is celebrating it. The hit show is returning this fall and they have released some new art as well as a teaser clip. Fans of the long-running comedy have desperately been waiting to see if Glenn Howerton's Dennis will be on the show when it returns. Howerton also stars in A.P. Bio, which was just recently picked up for a second season. However, Howerton has maintained that A.P. Bio is not the reason that Dennis left the bar.

FXX released some awesome new art for It's Always Sunny in Philadelphia, which features a Friday the 13th-inspired look. Charlie Day, Rob McElhenney, Danny DeVito, and Kaitlin Olson are all seen running away from a cabin with a mysterious figure in the background wielding an axe that looks an awful lot like Jason Voorhees. Could the man behind the hockey goalie mask be Glenn Howerton's Dennis? If it is, the rest of the gang doesn't look so happy to see him.

Dennis has had some serial killer fantasies on It's Always Sunny in Philadelphia, so it's not too far of a stretch for him to be like Jason Voorhees. The character also has some pretty well-documented sociopathic tendencies as well, so it could very well be him in the mask. Additionally, if the Jason Voorhees-looking dude in the art is supposed to represent Glenn Howerton's Dennis, what does it all mean? Will he be a murderer in Season 13? Or is this just pointing out that Howerton will have little or nothing to do with the show when it premieres in the fall?

Season 13 of It's Always Sunny in Philadelphia picks up right after the Season 12 cliffhanger where Dennis said goodbye to Paddy's Pub to go be a dad in North Dakota. The official FXX synopsis for Season 13 has Mac (Rob McElhenney), Charlie (Charlie Day), Dee (Kaitlin Olson) and Frank (Danny DeVito) back, as always, at Paddy's Pub, but Dennis reportedly won't be there. At the beginning of the year, Glen Howerton released a lengthy Twitter thread that would not confirm nor deny that Dennis was going to be coming back to the bar. He said that if he revealed the news at the time, that it would ruin the entire storyline for Season 13.

While Glenn Howerton's involvement in Season 13 of It's Always Sunny in Philadelphia is currently a mystery, we know that the show will premiere on FXX Wednesday, September 5th. While Dennis is a mystery, the new teaser art certainly implies that something weird is going on, or at the very least, they're playfully messing with their huge fan base. Whatever the case may be, it's all very much in the spirit of It's Always Sunny in Philadelphia. You can check out the new art as well as the brand-new teaser video below, thanks to the It's Always Sunny Twitter account.