Santa’s Little Helper

From The Simpsons - Wiki on Neoseeker

Santa's Little Helper is the family dog of the Simpson family. He has been part of the family since the first episode, "Simpsons Roasting on an Open Fire", when he was picked up by Homer and Bart after losing in a Greyhound race that Homer had been depending on. Despite losing the race, and thus Homer's Christmas money, Homer decided to take him home, where the family realise that they have gotten the best present of all; something to share their love.

Although he doesn't speak, his barks and other noises have been provided by Frank Welker and Dan Castellaneta over the years.