At around this time Marvel came out with their limited-animation style cartoons, from Captain America to Sub-Mariner, Fantastic Four, Hulk, Thor, and Spider Man, and the comics were filled with constant advertisements to this enterprise. The ads even went so far as to name the specific stations in each region that showed them (including stations in countries around the world).
So I find it ironic that around this time they also started showing ads for competing cartoon blocks, especially this one, which included Superboy and Krypto, the Super Dog.
This was around the first peak of Marvel-DC rivalry, as Marvel's fare was starting to take root in America's collective consciousness, and DC was fighting hard to maintain their position as status quo.
The rest of the shows are also noteworthy as among those that brought rise the end of the golden age of animation, and the beginning of low-budget Saturday morning cartoons, the same kind that would eventually become parody fodder for Cartoon Network and Adult Swim.
This was among the first of a new breed of comic book ads that were more colorful, less wordy, and more aimed towards younger kids. These are the kinds of ads I loved reading in the 80's, and look forward to featuring more of as they go along.
For some reason I can't figure out which issue I ripped this ad from, but they ran around 1966.