The show's early history was somewhat rocky, going on and off the air a number of times. Viewers, however, rallied around the show once it expanded to a half-hour format.

The feature came about when Cartoon Network was looking for some longer-format material to air. At the same time, Atoms had been thinking about pitching a longer story featuring the characters. His first pitch, Billy & Mandy Vs. the Martians, was declined by the network -- "There were too many zombies," Atoms says -- and became an episode in the series instead. Atoms' back-up idea was Big Boogey Adventure.

"It's sort of our Wrath of Khan tale," he explains. Like the Star Trek film The Wrath of Khan, which centered on a villain that had appeared in just one episode of the classic television series, Big Boogey Adventure features the Boogey Man, the series' only real villain, who also appeared only in one episode. (The 2004 original short, Bully Boogie appears on the DVD as an extra, along with a behind-the-voices featurette.) "I hope it will be a fun movie that the fans will really like," Atoms says. "You'll learn some things about the characters, and there are a lot of good jokes in it."

While the show is about to finish its run and Atoms is creating a new pilot for the network, the Billy & Mandy characters will continue to live. Atoms has a Halloween special in the works that he describes as sort of a spin-off of Billy & Mandy. Billy, Mandy and Grim will make an appearance in the special, but it will focus on some of the series' secondary characters, such as Irwin.

Atoms believes Billy & Mandy's longevity is due in large part to the three main characters and their relationship with each other. "At its core, it's about three friends," he says.

Karen Raugust is a Minneapolis-based freelance business writer specializing in animation, publishing, licensing and art. She is the author of The Licensing Business Handbook (EPM Communications).