Horton-Doo is the "mad scientist" uncle of Scooby-Doo.

Physical appearance

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

Season three

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.



  • Horton Doo appears in Capstone's Scooby-Doo! Encyclopedia despite being past the book's cutoff date of 1985.