Cthulhu famously makes an appearance during the intro scene of Rick And Morty, but will he ever actually turn up during an episode? Rick And Morty is an Adult Swim series following genius scientist Rick Sanchez and his grandson Morty, who hop around the galaxy meeting all manner of colorful characters. The trouble is their adventures usually end with bloodshed or severe emotional trauma, with the show being a skillful blend of comedy and sci-fi.
Rick And Morty regularly pays homage to classic movies and TV shows, dropping references to everything from Die Hard to A Nightmare On Elm Street or Ocean's Eleven. Since season 1 Rick And Morty's title sequence shows several random scenes, with only some of them being clips from actual episodes. It always opens with a shot of the titular characters running away from some alien creatures, before Rick jumps into a portal and leaving Morty stranded as the monsters are about to attack. It also always ends with a clip showing Rick, Morty, and Summer in the space cruiser fleeing from Cthulhu, after they appear to have stolen a baby Cthulhu.
Cthulhu was created by H.P. Lovecraft and this creature is a powerful cosmic entity that is one of the author's Great Old Ones - AKA a race of God-like beings that once ruled the Earth. Cthulhu is easily the most famous of Lovecraft's deities and has been immortalized in everything from video games like Call Of Cthulhu: The Official Video Game to plushy toys. Despite Cthulhu's presence in the opening of Rick And Morty, the being has yet to appear on the show itself.
Considering about half the clips shown in the Rick And Morty opening haven't made it onto the series yet either, this isn't a huge surprise. Co-creator Justin Roiland has stated the fun with the intro sequence is trying to guess which of the clips will show up during a given season. He and Dan Harmon (Community) have mostly played coy about Cthulhu appearing but did admit during an SDCC 2019 appearance that there's a "part two" to the Cthulhu scene that might show up in a post-credit scene one day.
Seeming to immediately regret saying that out loud, Roiland would somewhat walk back the comment, before confessing they had planned to add a Cthulhu moment to a Rick And Morty season 4 episode but later removed it. It seems there's a desire to have Lovecraft's monster show up on the series someday, but they haven't cracked how to do it just yet. So Cthulhu will almost surely make some kind of Rick And Morty cameo in the future - and hopefully, it will explain why Rick and company stole his baby.