Which Episodes Star Guillermo Del Toro And Who Does He Play?

Not everyone would be willing to play a lunatic patriarch of inbreds on "It's Always Sunny," least of all a venerable filmmaker. Such is the friendship between Guillermo del Toro and Charlie Day. The pair first worked together on del Toro's 2013 cult favorite "Pacific Rim."

For Day, "Pacific Rim" was eye-opening — so much so that he tried to incorporate some of del Toro's filmmaking techniques in the horror-inflected "The Maureen Ponderosa Wedding Massacre." After getting the preliminary shots, Day asked director Richie Keen if they could do what he described to Conan O'Brien as "a few Guillermo takes." That inspiration has persisted on "It's Always Sunny," the episodes of which have become more experimental and ambitious over the years. "[We] just started using more, as I called them, 'Guillermo takes' throughout the show, and just getting more and more inspired to do more filming and make more things."

Del Toro has continued to be instrumental in Day's filmmaking journey, even giving Day notes and guidance for his directorial debut, "Fool's Paradise." "I owe a massive debt of gratitude to Guillermo Del Toro," Day told The Hollywood Reporter. "I would send him pages, and he would send them back with his notes. But he really helped guide me, and he gave me the confidence to just go ahead and do this reshoot."

With Day and del Toro seemingly tighter than ever, it's not outside the realm of possibility that Pappy McPoyle will rear his bird-wearing head on "It's Always Sunny." The trailer for Season 16, which premiered on June 7, even promised a grand McPoyle return.