I read that Jack Kirby designed the characters.
Was he the guy who did Heavy Metal?
Dear God, protect us from the heathens! Heavy Metal was a collaboration of artists who were regular contributors to the magazine of the same name.
Jack Kirby was one of the "grand old men" of comics, having sat right there with Stan Lee helping to create characters you know and love today. After a slight(life-long) difference of opinion with Stan the Man, Kirby went to DC, where he created his famous "Fourth World" titles as an alternative to accepted DC canon. Although dead for many years now, his ideas lived on, including OMAC and the New Gods, Darkseid and his minions, Big Barda, New Genesis, etc. Try Wikipedia for more detailed info-the guy really was a founding force in comic books.
And, yes, I believe Kirby did create Thundarr. Among other things.
Ok, cool. I didn't know about all that, sorry.