Ruby-Doo is a female Great Dane. As a puppy, she had yellowish brown fur with a head of brown hair tied into a pontytail. She wore a pink sweater with purple rims, and a legwarmer on her tail. Fully grown, her hair had gone and her fur had become pink, and she wore a pink bow on top of her head.
- The Richie Rich/Scooby-Doo Show: In "Scrappy's Birthday", Ruby-Doo appears in a flashback to Scrappy-Doo's birth.
- A Pup Named Scooby-Doo: In "Curse of the Collar", Ruby-Doo attended the Doo family reunion at the Knittingham Puppy Farm. As a puppy, she related a lot to Daphne Blake, sharing a common interest in fashion.