It's possible you're thinking of:
* "The Thorn": This is a mysterious being from the Scooby Doo episode "A Night of Fright is No Delight." However, it doesn't have a name or character associated with it.
* "Thorn" as a potential name: Perhaps you're thinking of a specific character with a similar name in a Scooby Doo episode or movie?
Could you give me more information about the context or specific episode/movie where you saw this character? I'll be happy to help you identify them.