In "Doctor Doom, Master of the World", the Latverian monarch abducts the President and places him under mind control. I've said in the past that I had assumed that Brad Crandall, long the voice of Sunn Classic Pictures, voiced Doom, but a Wikipedia entry claims that it was Ralph James (Mork & Mindy) who essayed the part. Judge for yourselves.
Note, too, that Spidey/Peter Parker is voiced by a different actor than on Amazing Friends. Seems Marvel's then-nascent television arm, formerly DePatie-Freleng, was still finding its way, as it would have made more sense to use the same actor on both shows.