The White Dog is a stray dog that tries to attack Bart in the episode, The Lastest Gun in the West.
Background[]
The dog used a friendly look to make everyone except Bart to like him, and to make Bart first believe that he was a good dog. He was briefly adopted by the Simpsons Family and was calmed from chasing Bart by Buck McCoy. Later, at the end of the episode, he can presumably seen chasing Bart again.
This dog's on-screen name is Rover, and it has acted alongside Rainier Wolfcastle in at least one film as seen in Special Edna.