The Sub-Mariner

This was the Sub-Mariner's sole animated series. The character was Marvel Comics' first and mightiest mutant, and had been a staple of Marvel Comics since the early 1940s, when he was first introduced. It was also the series in which the Uncanny X-Men made their television debut, in Doctor Doom's Day/Doomed Allegiance/Tug to Death (1966). The plot was based on a Fantastic Four story, but because their television rights belonged to Hanna-Barbara, the Four were supplanted by the X-Men.