Hanna-Barbera, for the 2nd straight season, sold CBS a two-feature series where the headline star was in the middle feature, and thus isn't quite as remembered today.
Moby Dick was a loose adaptation of Herman Melville's classic novel, but this time, Moby, like King Kong a year earlier and Godzilla 11 years later, was rebooted as a hero, guarding a pair of shipwrecked kids, Tom & Tubb, and their pet seal, Scooby, as they travel underwater on exploratory adventures.
Mightor was on a prehistoric planet, which could easily be ret-conned today to be somewhere on the Herculoids' home planet, Quasar (known as Amzot back in '67). Some might think, as I did at one time, that Mightor could just as easily have been one of the world's first real superheroes, 10 years before H-B introduced the campy Captain Caveman, who was billed as "The World's First Superhero".
As it was, Mightor starred in 2 shorts per week, with Moby in the middle, same as Frankenstein, Jr. & the Impossibles the previous year.
Here's the basic intro:
And, a variant with narration by Don Messick: