Billybot was a robot version of Billy created by Creeper that appeared in "Billy and Mandy's Big Boogey Adventure". He was apparently smart, but became like Billy when Harold gave him root beer and he malfunctioned. He started drinking more root beer afterwards, and kept blowing his own head off. At the end of the movie, he and Mandroid forced Creeper to be their slave. They also transformed to fight crime. Unlike Mandroid, Billybot retained his obsession with assimilating Billy and immediately attacked him when Billy offered friendship. It is also a themed note of Billybot to say the emotion of the next statement he is about to say (similar to HK-47 from Star Wars), such as:
- Query (Question)
- Statement (Flat sentence with no intention but to say something relevant)
- Exclamation (Yelling, shouting, anger, or some kind of extreme emotional discharge)
He was once smacked like by Mandroid when he said something stupid which somewhat also lead to his malfuctioning.
- "Statement: If I had known robots had to pee I wouldn't have had that 32oz liquid coolant right before we time traveled."
- "Statement: I LIKE PIE!"
- "Statement: DESTROY US ALL!"
- "Statement: I am dreaming that I am a pygmy marmoset."
- "Exclamation: ASSIMILATE! ASSIMILAAAAAATE!!!!"
- Him & Mandroid were costumes for Billy and Mandy in the games The Grim Adventures of Billy & Mandy video game and Cartoon Network: Punch Time Explosion (Console version).