The Demons are the supporting antagonists who serve as Scrappy-Doo's henchmen from the 2002 film Scooby-Doo.
Like any monster, the Demons were easily duped and used brute strength to get things done. They served Scrappy-Doo loyally and even attending training sessions on learning how to behave like a teenager. The demons didn't attack any of the employees, particularly N'Goo Tuana and Zarkos, who are allied with Scrappy, showing they know who's on their side. Unfortunately, their weakness is being exposed to sunlight which results in smoldering glowing spots to form all over their bodies, before making them explode.
The demons appear as nine feet tall violet reptilian monsters with darker spots over their bodies and green eyes.
One of the demons is seen as Scooby-Doo is lured to a bag of hamburgers. He then tries to capture Scooby, but fails when he chases him up a palm tree which catapults the demon to a roller-coaster ride.
Later that same night, a few of them break into the hotel and capture Fred, Velma, Mondavarious and the college students, except for Scooby, Shaggy, Mary Jane and Daphne who escape. The demons then drag the bodies of the captured tourists into their hideout.
It turns out that they were in their victims' bodies in daylight when Velma's protoplasm returns to her body, a demon emerges from her body as well. Once exposed to sunlight, the demon then explodes. Later when Fred's protoplasm enters Daphne's body (who was possessed after getting captured by Zarkos), a demon comes out of her body and Velma exposes it to sunlight by opening the blinds in a room, disintegrating the demon.
Aware of the demons' weaknesses, the Mystery gang used a skeleton head disco ball in the ritual chambers as their plan to reflect sunlight when the souls return to people's bodies. However, their plan backfired when Shaggy got caught on the vat of souls. Fortunately, when Daphne defeats Zarkos, he falls down the well and onto the vat of souls and knocking it over, releasing all of the souls which return to people's bodies. When the demons emerge from their bodies, they instantly explode as the disco ball reflects sunlight from the open well.