IMHO Eddie (Frasier) is possibly the best TV dog ever. He actually seems to have acting talent and comedic timing.
My favorite TV dog, however, is Dreyfuss (Empty Nest). Just a big goofy lovable dog.
I also liked Murray (Mad About You), even though his funniest moments were nothing but sound effects (whump!) when he wasn’t even on screen.
The thread is open to all things TVdog-related (annoying TV dogs, great TV dog moments, etc.).
There is no other-Buck Bundy. He was a French briard named Mike rescued by trainer Steven Ritt from the pound and I always though he fit in perfectly with the family and neighbors. He was left ungroomed to look sloppy on the furniture for a while and, while a lively creature in his own right who knew about twenty-five commands, looked great lying on the couch or begging for food. He could even turn his head away in disgust or escort girl dogs upstairs, and was often used for sight gags and interactions with the neighbors (there was one episode where his neutering led to a big Steve/Marcy argument about neutering him once they had their 2 perfect kids). In later seasons he had his own voiceovers, usually by writer Kevin Curran but once by the great Cheech Marin. In 1995, when Mike had to be retired because of hearing loss, he even had a whole episode dealing with his death, “Requiem for a Dead Briard”. Mike himself died in 1996.
In fact, he had several episodes where he was the main character, including Buck the Stud and Look Who’s Barking.
Which B.B. King himself was in.
And wrote a song for him called “Buck’s Lament”.
I rest my case.
The best TV dog of all time – winner and still champion – was Cleo from The People’s Choice
Second was Neil, from Topper.
Finally, Rin Tin Tin. You can have Lassie; Rinty was far better.
Do cartoon dogs count? In that case, I nominate Santa’s Little Helper from the Simpsons.
I have a dog who’s half Jack Russell (though 150% Jack Russell by temperament) and I’ve wondered how in the hell they ever kept the dog they used for Eddie still enough to film anything. With mine you’d either see him sleeping, cuddling in somebody’s lap, or else a white and red blur.
The Quest dog:
Bandit.
Astro
Wishbone!
RealtyChuck and I are on the exact same page! I loved Cleo so much - Santa brought me a stuffed toy Cleo (no idea where my parents found that!!) and she remained with me through college. Unfortunately, she was in a trunk which was stolen over 30 years ago and I have never been able to find a replacement. 
I should clarify here that the stuffed animal wasn’t one specifically made to go with the TV show. It was simply a stuffed basset hound toy that had a sqeaker in one ear. I do check ebay from time to time, no luck so far.
Rinty was my second favorite dog of childhood - when the Rin Tin Tin music played, I apparently dropped everything to see Rinty. I think that was probably the combination of the western and the dog. I still enjoyed Jeff’s collie, mind you. And then Lassie and Timmy.
Buck Bundy also gets my vote for all the reasons given by Mehitabel.
Scooby Doo. He’s hands down the best TV dog ever.
Came in here to nominate Moose (or Eddie) from Frasier. Though his son Enzo did a good job, too. When Moose got on in years, his son Enzo replaced him.
John Mahoney (Marty Crane on Frasier) even said that he didn’t view Moose as a prop but as an actual fellow actor.
Definately Rinty. We’d always gather around the TV to hear Rusty yell “Yo, Rinty!” and watch a villain get gnawed by a dog. It was even better than Fury, where the villain got stomped by an enraged horse.
He’s a cartoon dog and he’s on film, not TV, but I’m partial to Gromit.
Shit yes. Lucky could never fill his shoes.
I like Buck Bundy too, but in terms of acting ability, if a dog can have that, I think the dog from Petticoat Junction leaves the rest of them far behind. His name of Petticoat Junction was just Dog, which may seem odd but considering the three girls and the baby were all named XXX-Jo, I guess imaginative names weren’t valued in the Hooterville Valley
Of course this Dog was really named Higgins and he went on to play Benjiin the movies