Which rejected Cartoon Network pilot first used the Rick and Morty theme song? Dog World used it first.
Composer Ryan Elder originally wrote the theme for a different Justin Roiland project, a proposed animated series about people transported to a world inhabited by intelligent, human-like dogs. That project was called Dog World and did not become a series. When Roiland and Dan Harmon developed Rick and Morty, Elder’s existing music suited the show’s oversized science-fiction mood, so they reused it.
The connection is not merely an internet fan theory. Rick and Morty’s first-season episode “Lawnmower Dog” echoes the abandoned concept when Snuffles becomes highly intelligent and the dogs decide to establish a world of their own. The episode’s premise therefore doubles as a playful reference to Roiland’s earlier pitch.
A common mix-up is to treat the Rick and Morty theme as music composed from scratch for the 2013 series. Its composer was Ryan Elder, but the melody’s earlier home was Dog World. The other listed choices are unrelated projects or titles.