The Tar Monster is a villain that debuted in The Scooby-Doo Show episode of the monster's same name.
The Tar Monster first appears scaring some construction workers away from a section of Byzantius. He turned out to be a criminal named Mr. Stoner who was trying to steal the treasure from the Inner Sanctum of Byzantius, but got foiled by Mystery Inc.
- Tar Monster appears in Scooby-Doo and the Cyber Chase as one of the virtual versions of the original monsters assembled by the Phantom Virus to attack Mystery Incorporated but got deleted from the internet when Scooby grabs the last box of Scooby Snacks.
- Tar Monster appears in Scooby-Doo 2: Monsters Unleashed as one of the monster costumes stolen from the Coolsonian Criminology Museum and then brought the life by the Evil Masked Figure in order to get revenge on Mystery Inc. Tar Monster was later killed when Scooby reverses the polarity in the Monster Making Machine, turning all of the monsters (including Tar Monster) back into costumes.