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
He met Shaggy, Scooby and Velma in his lab where he showed them his scary stuff which led Shaggy to think he's Nasty-Doo. He was proven to be innocent after the case was solved. (The Were-Doo of Doo Manor)