- Species: Gorilla/Kangaroo
- Gender: Male
- Alignment: Evil
Little is known about this half-gorilla, half-kangaroo baddie. He was one of the contestants summoned by Uka Uka during a competition between him and his brother Aku Aku. Rilla Roo uses his large tail to attack and supposedly doesn't like to get his picture taken.
- Rilla Roo was originally named Kanga Rilla during development.
- He was featured on MTV Multiplayer's blog as part of their article, "Who Is The Best Video Game Monkey, Ape Or Other Primate?". The Doom Monkeys were also featured in that article.
- Contrasting every other character in the PlayStation games, Rilla Roo had no backstory and was never brought back after his debut Crash Bash, not even for a cameo appearance.