Kelp monster (Scooby-Doo! and the Legend of the Vampire)

The Kelp Monster haunted a cruise ship with the Shark Creature and the Peg Leg Captain.

Scooby-Doo! And The Legend Of The Vampire
Scooby-Doo and Shaggy Rogers were on a sea serpent and Scooby popped it with his claw. It landed on the Kelp Monster, the Shark Creature, and the Peg Leg Captain. Velma Dinkley unmasked the three creatures and it was revealed that the Kelp Monster was a person with black hair, the Shark Creature was a bald man, and the Peg Leg Captain is a person with white hair.

Appearances

 * Scooby-Doo! And The Legend Of The Vampire