Underdog was made by Leonardo Productions, makers of Tennessee Tuxedo. He was a cartoon character; imagine if Superman was a dog.

He had an alter ego, Shoeshine Boy. Whenever he heard a call for help, he'd run into a phone booth, there'd be an explosion, and Underdog would fly out. He'd usually speak in rhymes, then do battle.

Every so often, he'd use his "Underdog Super-energy pill" hidden in a compartment on his ring.

Funny, there was a bad guy on the show called Riff Raff, which predates Rocky Horror. Nowadays, Underdog's got a float on the Thanksgiving Day Parade.

From Yesterdayland.com:

Two other cartoons shared the Underdog show: The Hunter and The World of Commander McBragg. These segments had been seen before, in King Leonardo and His Short Subjects.

In its second season, Underdog switched networks and replaced The Hunter with Go Go Gophers, a show about two Native American gophers who were being driven off their land by the local cavalry. Every week, Col. Kit Coyote would have a different plan to eliminate the gophers, and every week, he would be outsmarted by the clever duo. The Colonel’s second in command, Sergeant Oky Homa, often tried to warn him, but to no avail. For whatever reason, the only remaining tribe members were the two gophers: Running Board, the leader, and Ruffled Feathers.

The other new segment, replacing Commander McBragg, was Klondike Kat, a feline Mountie who was perpetually on the trail of the thieving mouse Savoir Faire ("Savoir Faire is everywhere"). Every episode would feature Klondike hatching an elaborate plan to capture his foe, shouting his familiar threat, “I’ll make mincemeat out of that mouse!”