Linny the guinea pig.
The aforementioned Just’a Lotta Animals had Super-Squirrel, who was from the planet Chipton.
Aardvarks - add Cyril and Cedric Sneer from The Raccoons.
There’s a whole lotta different bugs in the Maya The Bee cartoon
I remember a Mighty Mouse episode that appeared to feature a statue of The Sloth in some Super League headquarters, only it turned out it was the actual hero, and he’d spent the entire episode slowly (but powerfully, it turns out) delivering one punch to the villainous Cow who’d taken out all the other heroes.
Cat and Mouse:
There’s Catnip the Cat and Herman the Mouse from the old Harvey cartoons.
Flea:
Tex Avery used fleas on a couple of occasions. In one, it was the classic “boy and girl in love, villain kidnaps girl, boy makes heroic rescue” story, only with fleas. The dogs and the rest of the world were just passive backdrops. The hero was named, IIRC, Flea-Wee.
In another Tex Avery cartoon, Droopy Dog is a huge fan of Dixieland music but can’t find anywhere to play his record. He ends up hijacking a flea circus of musical fleas and becomes a stage sensation when people think he’s magically producing Dixieland music out of nowhere. At the end, the trumpet-playing flea (also named, I think, Flea-Wee), reveals that he’s the narrator of the story.
Am I the only person here who watched Seabert as a kid?
This was a French Canadian kids’ cartoon with an environmentalist theme. It featured Tommy, a little white kid, and Aura, a little Eskimo girl (who I had a giant crush on as a little kid.) This pair would travel all over the world fighting to save endangered animals from comically bumbling, buffoonish villains, including a guy named Graphite who looked like an evil Inspector Gadget and sported a huge nose and a New Yawk accent. It had a great animation style and a good soundtrack.
I re-watched some old tapes of it a few weeks ago and was struck by how innovative the soundtrack was, often featuring Moog synthesizers. I was also struck by how many times Aura, the little Eskimo girl, landed in situations where she would be tied up by the bad guys. :eek:
Those have to be close to the limit of where such characters can go. I suppose having a sub-atomic particle has been done?
Nick Neutron
Monty Muon
Ted Tachyon
Bill Boson
Emil Electron
Fighting crime and stopping world hunger. Coming soon to a petri dish near you/
Now that you mention it, I suppose Aesop had a hand in it, too.
This made me remember the rabbit in Monty Python and the Holy Grail. Not to mention the catapulted cow.
Also Cerebus the Aardvark.
Characters like Chanticleer the cockerel and Reynard the fox go back to Chaucer at least.
What about weird meta-cases, like where an anthropomorphic dog has a pet dog? I always wonder about that. We have cartoons like Arthur/Pal and Mickey Mouse/Pluto where anthropomorphic animals have pet dogs and also interact with anthropomorphic dogs, but for some reason the anthro-dogs are never the ones with pet dogs. This gives the cartoon a creepy Dr. Moreau subtext. Can anyone come up with an example of an anthropomorphic animal that had a pet that was ostensibly the same type of animal?
How could we forget Brian from Family Guy?
A very weird case, since he was an ordinary dog with dog limitations (leash laws and a 12-odd year lifespan, for example), but human intelligence and speech. There are many other dogs, but he and Jasper seem to be the only ones who can talk. More than once this is commented on in the show, but rarely causes any deep concern.
Other Family Guy animals: Jasper (dog) and The Chicken (chicken).
Well, there’s Superman and Krypto. Though they resemble a human and a dog, they’re actually alien life forms that no doubt have biologically far more in common with each other than they could with any Earth species.
Ditto Zan and Jayna and their pet “monkey” Gleek.
Super Gnat is a character in the Phule’s Company series by Robert Asprin.
Admittedly, she’s actually a human woman, albeit rather short. 
I think it’s humorously ironic that Spongebob Squarepants - a sponge, obviously - has a snail for a pet, which in the real world is a much more complex animal (relatively speaking) than himself.
Close enough. At least I figured out he was some kind of rodent. :smack: