Quaker Oats went to the well again, commissioning Jay Ward Productions to create a new animated character to promote their cereals, after Cap'n Crunch, Quisp, & Quake.
Enter, then, the land of King Vitaman. The original incarnation, created by the Ward crew, was a tiny fellow (voiced by Joe Flynn, ex-McHale's Navy) who had bumbling knights for assistants, predictably enough. After a couple of years, Quaker switched gears and went with a live-action actor, George Mann, a former vaudeville star, as the new King.
For what it's worth, King Vitaman, like Quisp, is still produced in limited quantities and areas. Most folks only see the Cap'n Crunch line of cereals and Quaker oatmeals, but little else.
Now, let's move back in time to 1970 and see King Vitaman as he originally appeared.