Mine have to be Ladyhawke’s Friesian stallion
Othello
And the dearly departed
Bart the Bear, who found his way into a surprising amount of camera time, including:
More info about Bart can be found here
I love Bart the Bear! I didn’t know he died.
Some of my other favorites:
That commercial dog, I think his name is Duke, who was featured in Nissan’s “Dogs Love Trucks” commercials, and the one where he steals the SUV and drives around picking up his doggy buddies. He looks a lot like a dog I had.
The cat from Early Edition.
Flipper.
Fred, the bird from Baretta.
I’d love to get a copy of a “Funniest Home Video”-style short featuring a small black-and-white kitten and a full-grown orange cat. The kitten is facing the cat and frantically waving his front paws in a gesture that was, I guess, supposed to be menacing or something. The cat stood perfectly still through all of this until the kitten stopped. Then the cat jumped on the kitten, flattening him. It was hysterical.
Bryan Ekers, I had a copy of that clip! I kept it on my desktop at work, but it went into cyber heaven when I had a computer crash. I’d love to get another copy of it someday.
Great jumping horny toads, look at the size of that bear in the link. Part of the reason I was always fascinated with Bart the Bear was his sheer size. His head is almost the size of a man!
I’m putting in a vote for Eddie (“Moose”) from Frasier.
Champion The Wonder Horse
Lassie
and the dog from The Littlest Hobo
This bird and I go way back. Back to when I was 3 and younger (1977 and back). This was the only time in my life that I had exposure to the show, but that bird is still etched in my head to this day. Just a few years ago I randomly asked my Mom, “What was that show from the 70’s with the big white cockatoo? It had some dude in it.” The bird was my only point of reference to the show or my memories.
Up untill age 3 we lived in Orange County and had access to what I assume was robust local programming. After that we moved up to Humboldt where you were lucky if you could watch 2 channels, and at least required someone standing way up on the roof, on one foot, holding the antenna in one hand and a ball of tinfoil in the other.
I happen to be owned by almost such a pair. Dexter (small yet full-grown 6yo male black and white shorthair), and Peaches (average to large framed 3yo male orange tabby shorthair). I can approach them with the idea of a re-inactment. How much tuna would it be worth to ya? 
Well, I happen to know/have known, several stars of the large and small screens, including
Doriana, the red eyed tree frog from the Telus ads
Mr Dick, who hung from a cheetah’s tails, likewise for Telus.
Francis the ferret, Mattel toys ad.
Two ferrets (whose names I forget), Jack the crow and Ben the rat who all appeared on “The Fearing Mind”, a short-lived TV show.
Wolfie, who was on Danger Bay and, I think, Littlest Hobo.
There are also a number of critter’s who have appeared in print ads.
My favorite is my own deer mouse, Fallow, who was in the Canadian Wildlife magazine’s kids edition, on the back cover and also in their 2003 calander. She was in a kid’s book on mice too.
Well, yeah, it helps that I work in a zoo/animal talent agency. 
I’m tempted to give an honorable mention to all of Marc Morrone’s Pet Squat, even though the guy seems a bit screwy to me.
He acknowleged on a Martha Stewart episode once, that all of the animals that he dumps in together for during the show are all self-selected to be very cool cucumbers in the proximity of multiple other species, even mortal enemies or predator/prey interactions. It is amazing to see some of these animals tumbling over one another.
The only other thing I’ve seen that comes close was with the seafood scraps from a restaraunt that used to be in Shelter Cover, California, called Pelican’s Landing . All sorts of scraps, cuttings and other delicacies were heaped up and set out on the deck right in front of the large windows of the restaurant. The goodies were served up to any animals who are willing to wait in line for it. Racoons, cats, rats, pelicans, seagulls…you name it, all patiently waiting their turn at the pile, all for an enthralled studio audience.
Great food too.
Jake, the Cat from Outer Space
It was one of my favorite movies as a kid
and what the heck. Porthos, the first beagle in outer space
Arnold Ziffel.
You gotta love Toto.
He also appeared in about 10 other movies.
Then there is Benji who was also the dog on Petticoat Junction.
My favorite, Draco who played Diefenbaker on Due South
I love Eddie from Frasier. I swear that dog is smarter than most people. He’s such a cutie.
Breezy the beagle, who plays Porthos on Enterprise.
He (she?) only had a bit part, but I thought that moth Gandalf used as a messenger to the eagles in Fellowship of the Ring was great. It really seemed to be listening to his instructions.
Asta from the old Thin Man movies with William Powell and Myrna Loy.
The dog in Dana Carvey’s so-so movie Clean Slate – wears an eye patch for a depth perception problem and is constantly bumping into things. Funny.
I really liked the recent Viggo Mortensen film Hidalgo. The horse who played Hidalgo - T.J. - was excellent! A lot of personality. I heard that Mortensen bought T.J. (from Disney?) afterwards. They made a great screen couple.
Just looking at the credits list for Hidalgo, I’m pissed that T.J. was uncredited. I hate that. :mad: Mickey Rourke’s little dog in Once Upon A Time In Mexico wasn’t credited either. The Internet Movie Database doesn’t list the dog either, but I believe I read an article/interview with Rourke which mentioned it by name. (Although that could have been Rourke’s own pet that was mentioned.)
Does anybody know of any good, extensive websites out there dedicated to animal actors past and present. IMO, they should always get a credit, even at the end of the list. (Though I would have put T.J.'s name on the Hidalgo poster. He played the title character, after all.)
Anyhoo…