Santa's Little Helper
description: This loveable, yet a bit dim, brown greyhound was found at the tracks on Christmas Eve.  He didn't win the race even though Homer betted on him, but he found a nice home.  Having a few obedience problems, he went to an obedience school...but it didn't really help much

Snowball I
description: This white cat was the Simpsons first cat, but got run over by a member of the Quimby family (Clovis Quimby).  Lisa has written a very gripping poem about her (I once had a cat named Snowball, she died she died, mum said she ran away, she lied she lied...why o why is my cat dead, couldn't that Chrysler have hit me instead?), and obviously misses her very much

Snowball II
description: This black cat was the second cat of the Simpsons.  He got run over by a car, so Lisa got a couple of other Snowballs after him.  They all freakishly died after a short while, but then the crazy cat lady gave her another black cat that survived.  Lisa named him Snowball II as well, and decided the other Snowballs should not be mentioned anymore

Pinchy
description: Homer bought this lobster as a little one with the idea of eating him when he got fat, but he got too attached and spoiled it.  Captain McAllister offered to take Pinchy in his school but Homer couldn't part.  Unfortunately Homer gave Pinchy a nice hot bath, which killed him, and ended up eating him anyway

Princess
description: This is the pony Lisa gets because Homer is afraid Lisa didn't love him anymore.  Lisa loved Princess very much, played the sax for her and everything, but eventually had to give her up because Homer had to work nights in the Kwik-E-Mart to be able to afford her

Duncan(Furious D.)
description: This white horse was originally used as a stunt horse, but didn't do a good job at it.  In order to prevent him from being sent to the dog food factory, Bart and Homer decide to keep him, and after seeing how fast he is, race him.  Duncan is intimidated by the other horses though, until Bart gives him a new name and punk-look

Laddie
description: This Lassie like collie is bought by Bart with his credit card.  It's an amazingly smart dog, who knows tricks, helps people, and so forth (even knows how to use the bathroom).  When the repo guys come to take all Bart's stuff away, Bart exchanges Santa's Little Helper for Laddie, in order to keep Laddie.  In the end Bart misses Santa's Little Helper too much though, so he gets him back from the blind man who got him, changing Santa's Little Helper back for Laddie

Mojo
description: Homer gets this helper with the idea that he'll be doing all kinds for stuff for him.  In order to get him he lies and says Mojo is for his father.  Mojo ends up living his life like Homer though, and eventually that's his doom

She's the Fastest
description: An amazingly good race dog, but her career gets cut short because she falls in love with Santa's Little Helper.  Not really her fault I suppose, he jumped on her during the race

Rover, Fido, Rex, Spot, Rover II, Fido II, Rex II, Cleo, Dave, Jay, Paul, Branford, Dave II, Jay II, Paul II, Branford II, Sleepy, Dopey, Grumpy, Donner, Blitzen, Grumpy II, King, Queenie, Prince, The puppy formerly known as Prince
description: These are the pups of Santa's Little Helper and She's the Fastest.  Mr. Burns steals them to be able to skin them to make a tuxedo, but Lisa and Bart make them all stand up on the hind legs like little Rory Calhouns, so eventually he can't go through with it and keeps them as (very successful) race dogs.

Stampy
description: Bart entered a competition on the radio, won and got this elephant.  His secret word is Magumbo, and for the rest...well...he's an elephant...enough said

The gold fish
description: A gold fish that lives in a tank...and had to share his tank with Pinchy for a while.  All there is to say really

The Koi fish
description: for one of their anniversaries, Homer bought a koi pond.  There are bound to be some fish in there, aren't there

The Screaming Caterpillar
description: this animal decided the koi pond would be a good place to stay, and Homer wasn't allowed to kill it because it's endangered.

A badger
description: He lived in Santa's Little Helper's dog house for a while.  Because of him, Homer found out there were two are codes for Springfield, one for the rich or intelligent, and one for the poor, causing Springfield to be torn in two, and brought back together by The Who

Maurice
description: This mule is not really a Simpsons pet.  It's the mule Bart got to know in France.  Funnily enough the mule got the better sleeping place

Strangles
description: The family bought this python as a new pet for Bart when Santa's Little Helper became a police dog.  When Santa's Little Helper came back in the family, Strangles went on to be Groundskeeper Willie's pet.