You know, I used to think that I had a pretty good grasp on the breadth and width of scary retro animation. However, it seems that every single week, some new piece of terrifying stuff comes up. Case in point: Super President from 1967. I mean...wow, I would love to see some more of this.
It's Paul Frees giving the narration here obviously (and apparently he was the voice of the titular character as well, according to Wikipedia) and it's an American president given superpowers. You know, sort of like Brian K. Vaughan's Ex Machina on blotter acid, only totally different.
Opening and closing credits plus groovy musical wonderment after the break.
Also, again according to Wikipedia, Daws Butler, June Foray, Don Messick and Ted Cassidy all provided vocal work on the show.