Except for one seemingly special white-furred one, the rest varied from orange, gray, and black. In the sequel, they were less realistic, but are seen in fur colors of orange, black, white, brown, gray, and blue, and a beige kitten.
The cats appear cute and cuddly, but this didn't stop Scooby-Doo's canine instincts from making him chase them. The different times he would get stuck while chasing them, they would either blow raspberries at him and mischievously laugh at him. When Mystery Inc. returned to the island, the cats acted feral, which due to being controlled by cat whistles used by fake were-cats. After the culprits were arrested, six of the cats (and possibly rest of the island cats) became docile, and had no animosity against the gang.
Scooby-Doo on Zombie Island
As the Mystery Machine drives onto the grounds of Simone's house, Fred Jones caught them on his camera. Scooby noticed them, too, taking the camera to focus right on them. He couldn't help, but chase them, tearing up much of Beau Neville's plants, much to his anger. When Scooby got stuck in a wheelbarrow's spokes, Daphne Blake told him to leave them alone. The white cat then blew a raspberry, in a cat-like tone, at Scooby. When Scooby got out, Shaggy Rogers caught one of the flower pots. Lena Dupree was not pleased with Shaggy, who claimed his dog was great with cats. When the white cat jumped on its owner, Simone, Scooby tried to slow down, but he bumped into her. Lena rushed to Simone as the cat turned around, and meowed with its closed eyes.
Later on, while Scooby and Shaggy were having a picnic, some of Simone's cats began helping themselves to some of their potato salad, as Scooby was about to have some himself. Once again, Scooby gave chase to the cats. During the chase, Scooby got stuck in a log, the cats laughed. When he freed himself, a frog was stuck over the top half of his head, making the cats laugh even more. Scooby managed to get the frog off and continued to pursue the cats, but only to end up falling in a river.
That evening, the white cat cuddled with Simone during dinner. In the kitchen, all of the cats returned to the house and began eating out of their dishes; Scooby still wanted to chase them. Shaggy went after him. The two then got cat food on their heads, and Scooby spotted the white cat, which hissed at him. Simone was annoyed, forcing Scooby to eat outside. Scooby and Shaggy went out to the back of the Mystery Machine, eating having crawfish and biscuits, as some cats spied on them. They were seemingly on trees, but then suddenly on the van. Shaggy decided to drive to a better place, making cats jump off, with Scooby blowing raspberries at them. Later on, when the gang heard them scream, the white cat scurried away.
During the final battle, some cats had been watching the fight. When Simone and Lena threw two zombies, this caused Scooby and Shaggy to be sent into the air as the cats watched them. After the werecats fell to dust, all of the zombies released their spirits so they could finally rest in peace. All of the cats witnessed this as they quickly flee.
The next day, as the gang was about to leave the island, Scooby was about to enjoy his sandwich, he noticed the cats that somehow got on the barge. Scooby just ignored them at first, but all of their eyes began to glow sinisterly, much to his horror.
Scooby-Doo! Return to Zombie Island
They were first seen on part of the island, looking feral. Then, while Mystery Inc. continued to help with the film, Velma who was wearing night-vision goggles, ran and told everyone to run. A harmless-looking beige kitten comes out and after a few seconds, roared like a tiger and breaking its cute kitten facade, which also signaled the other cats to attack Mystery Inc. and the movie crew, then three cat creatures appear to take Simone's pendant.
After the false cat creatures were captured, it turned out that the cats were controlled by cat whistles used by the culprits to do their bidding. With the cats freed, six of them explore the cave and dig up a chest, and since the legend said that the cats were the guardians of Moonscar's treasure, Alan Smithee claims it, declaring his retirement from the movie industry. The six cats were last seen resting around Shaggy and Scooby and one cat gulped a scooby snack.
- The sinister glow on the cats' eyes at the end of the film could suggest something more to them, such as a much longer lifespan (even immortality), since they were more than just house pets, they were creatures that Simone and Lena worshiped in the 1700s, meaning the cats in the flashback and Simone's could be one in the same, although, of course, this isn't directly confirmed.
- In a light-hearted post-credits scene, Scooby pours milk into two cats' bowls for them to drink.