This show was on the original "Captain Kangaroo Show". It was about a boy that could change into whatever he wanted to. Along with Mighty Dog Manfred they fought villains.

Tom Terrific was a child superhero, a shape-shifter who could transform into various animal and vehicle forms. He lived alone in a tree-house, with his pet dog as his only regular companion. Mighty Manfred the Wonder Dog was sentient and could talk, but was actually lazy and not particularly bright. He accidentally assisted Tom, when his words or actions inspired some of Tom's ideas. Tom had a rogue's gallery of adult super-villains, the only adults in his life. His archenemy was Crabby Appleton, a self-described "rotten to the core" man with no powers other than his intellect and an ability to come up with numerous schemes.—Dimos I