TenNapel was born and raised in the town of Denair, California. He started out as an animator on Attack of the Killer Tomatoes: The Animated Series. He soon began working in the video game industry on projects like 1993's Jurassic Park and Stimpy's Invention for the for the Sega Genesis and Jungle Book for the SNES and Sega Genesis. In 1994, he created Earthworm Jim, the character that would star in Shiny Entertainment's videogame, toy line and cartoon series. In 1996, working for Steven Spielberg's Dreamworks, he created for The Neverhood for the PC. The sequel, entitled Skullmonkeys, followed in 1998.
As for his film production, works on TenNapel's first feature length live action film, entitled Mothman, began somewhere in the late 90's, although as of 2002, that film was never finished. Regarding television, TenNapel was also the creator of the Project G.e.e.K.e.R. cartoon series for CBS, and was a consulting producer on the ABC series Push, Nevada with Ben Affleck.
As a graphic artist and cartoonist, TenNapel released his first comic book in 1998: GEAR, a surreal epic based on his real life cats, Simon, Waffle, Gordon and Mr. Black in a war against dogs and insects using giant robots as weapons. The cats from GEAR would eventually become the Nickelodeon series Catscratch. His second graphic novel, Creature Tech (2002), became the focus of a bidding war between movie studios. 20th Century Fox and Regency Enterprises won the war and are developing the script for a live action motion picture based on the novel.
TenNapel did the cover art for several of Five Iron Frenzy's albums, including a sculpture for their live album, Proof That the Youth Are Revolting. TenNapel has also created album covers and artwork for several Daniel Amos CDs, The 1999 tribute to the band, When Worlds Collide, the Neverhood soundtrack Imaginarium: Songs from the Neverhood and others.
Black Cherry, a graphic novel by TenNapel, will be released in July through Image comics.
TenNapel is also the lead singer of an independent band called Truck.