TenNapel was born in Norwalk and raised in the town of Denair, California. He got his primary education from Denair High School from 1980 to 1984. From 1984 to 1988 TenNapel studied at Point Loma Nazarene University on art specialty, finishing with Bachelor's Degree. He got a master's degree in art from California State University Fullerton in 2012.
TenNapel began 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 Sega Genesis and The Jungle Book for the SNES and Sega Genesis. In 1994, he created Earthworm Jim, the character that would star in Shiny Entertainment's video game, toy line, and cartoon series. In 1995 he left Shiny Entertainment and founded his own company, Neverhood, with several other former Shiny employees. Working for DreamWorks Interactive, Neverhood created The Neverhood for the PC and PlayStation. The sequel, entitled Skullmonkeys, followed in 1998.
On television, TenNapel was the creator of the Project G.e.e.K.e.R. cartoon series for CBS. He was also a consulting producer on the ABC series Push, Nevada with Ben Affleck. Towards the end of the 2000s, he also created two shorts for Frederator Studios and Nicktoons, "Solomon Fix" (computer generated 3D) and "Squirly Town" (traditional 2D).
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.
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.
Flink, a graphic novel by TenNapel, was released in late 2007 through Image comics. Monster Zoo, was released in early summer 2008. In June 2009 his graphic novel Power Up was released. In July 2010 his graphic novel Ghostopolis was released. It is being adapted into a film starring and produced by Hugh Jackman.
TenNapel produced an episodic spoof of Japanese Super Sentai-style shows called Go Sukashi! based on a character by Shoko Nakagawa (who appears in the films), and starring John Soares and Brooke Brodack. He has also published an online superhero-genre-spoofing webcomic titled Ratfist.
In September 2012, Fox Animation optioned TenNapel's published Graphix novel Cardboard, with plans for actor Tobey Maguire's Material Pictures, graphic novelist Doug TenNapel and the Gotham Group to be executive producers. Fox plans to have the picture developed under its WedgeWorks subsidiary. WedgeWorks director Chris Wedge (Ice Age) is producing, and is considering directing the film as well.
TenNapel and other former members of the Earthworm Jim team at Pencil Test Studios launched a Kickstarter campaign in May 2013 to fund a PC game project called Armikrog, described a spiritual successor to The Neverhood and also being animated using clay animation techniques. It was successful, and reached its stretch goal for a Wii U version.
TenNapel is a politically conservative Christian and has written articles for Breitbart.com's "Big Hollywood" blog.