An episode of the Ace Ventura cartoon had Ace go to a village to hunt down a killer moose; it later turns out that it was a weremoose. Almost everyone Ace runs into in the village happens to be a weremoose, with even his own pet monkey Spike getting turned into one. Later on, it turns out that the very person who brought him there is the original weremoose and has the power to transform at will via a special talisman and the very reason he brought Ace over to the village is so he could turn him into one, telling him that he'll be granted special powers and that together they'll create a race of moose men.
Ben 10 can turn into not one, but 10 (at least at the beginning, later he gets more) different aliens, each with a different super power. Part of the show involves him slowly learning how to better discern which alien's power best fits a given situation.
In the Codename: Kids Next Door episode, "Operation H.O.U.N.D.", Numbuh Five confronted her rival, Valerie, who was revealed to have the power to transform into a were-poodle. Earlier in the episode, Numbuh Five was attacked by a vicious dog who ate her homework, who was later revealed to have been Valerie in her were-poodle form.
An episode of Courage the Cowardly Dog had Muriel get bitten by a were-mole. Dr. Vindaloo (and possibly Eustace) are also turned into were-moles.
An episode of Dave the Barbarian has Dave get bitten by a cow and turn into a werecow. Also halfway through the middle he gets turned into other things like a cat, Oswitch, a hamster, Lula, an egg beater, a gym teacher, and finally... himself! But the twist comes at the end where Faffy ends up turning into a were-Dave.
The Dexter's Laboratory episode "The Laughing" had Dexter gets bitten by a pair of clown dentures, and he ends up turning into a were-clown whenever he laughs.
The werecar in the Futurama episode "The Honking". An evil robotic car named "Project Satan" has the ability to turn other robots (eventually including Bender) into four-wheeled cars who will run over other people on sight.
In the Kappa Mikey episode "Night of the Werepuff", there is a creature called a werepuff- it's a furry creature that eats clothes. Mikey gets turned into one.
In one episode of Regular Show, Rigby gets sprayed by a wereskunk. While the transformation can be reversed by getting smothered in tomato paste, a fully turned wereskunk will refuse to change back.
In another episode, Rigby accidentally summons Ybgir (a demonic version of him from another dimension). Ygbir looks and acts much like a werewolf, by scratching random people with his claws, which turns them into similar monsters. All of the transformations are reversed when Mordecai and Rigby send Ybgir back to his home dimension.
In the 1998 animated film Scooby-Doo on Zombie Island, Lena DuPrais, Simone Lenoir and Jacques (the film's antagonist) were werecats. They were referred to as "cat creatures" several times. Other occurrences of "cat creatures" have appeared on What's New, Scooby-Doo? and The Scooby-Doo Show.