The Mystery Kids' Mysteries is an American animated spin off of Gravity Falls featuring the extraterrestrial look-alikes of the Mystery Shack members (except Wendy).
- Delroy (Voiced By Jason Ritter) - Delroy is highly intelligent and expert in space sciences.
- Mabey (Voiced By Kristen Schaal) - Mabey is a girl with interests such as boys and fashion.
- Stoarge (Voiced By Alex Hirsch) - A grumpy man who drives Mystery Ship.
- Astro"Soos" Doo (Voiced By Ale Hirsch) - The pet dog who can speak.