Who is scrapy doo to Scooby Doo?

There's no character named "Scrapy Doo" in the Scooby-Doo universe. It seems like you might be thinking of a different name or perhaps a fan-made character.

Maybe you're thinking of:

* Scrappy-Doo: A mischievous and energetic nephew of Scooby-Doo, who was introduced in the 1979 series "Scooby-Doo and Scrappy-Doo". While he was initially popular, Scrappy later became a divisive character among fans.

* Scooby Dum: A dim-witted but lovable Great Dane who was introduced in "Scooby-Doo on Zombie Island" (1998). He's a cousin of Scooby-Doo.

If you have a different name in mind, please let me know, and I'll do my best to help!