Horton-Doo is the "mad scientist" uncle of Scooby-Doo.
He's a large brown Great Dane, he has a brown nose, wears a lab coat, a bow and small round glasses.
Horton-Doo is interested in science, monsters, and other scary things there are.
A Pup Named Scooby-Doo
- Horton Doo appears in Capstone's Scooby-Doo! Encyclopedia despite being past the book's cutoff date of 1985.