This sound editing company, Twenty-First Century Entertainment (formerly known as 21st Century Sound Design Corp.) was founded by Joel Valentine, and has worked on the following shows, movies and TV specials, mainly ones from Hanna-Barbera and Cartoon Network...
- 2 Stupid Dogs/Super Secret Secret Squirrel (2 Stupid Dogs segments only)
- The Halloween Tree
- The Town Santa Forgot (1993)
- What a Cartoon (many episodes)
- Dexter's Laboratory (first two seasons only)
- The Powerpuff Girls
- Samurai Jack
- Foster's Home for Imaginary Friends
- Korgoth of Barbaria
- Sym-Bionic Titan