John Hoyt
I was shocked to see him in this movie, his face being the most familiar and probably the only legit actor in this flick at the time it was filmed.
He was a character actor and so many of that genre can't even remember all the movies they were in--they could have parts in several movies a week, say their lines and move to the next movie or TV show. Its likely he didn't know what "Flesh Gordon" was about--just another bit part.
He will probably be best remembered as the Venusian with extra arms in the "Twilight Zone" episode "Will the Real Martian Please Stand Up" just as Barney Phillips will be best remembered as the Martian with the third eye in his forehead in the same episode.
"You may as well go to perdition in ermine; you're sure to come back in rags." Katharine Hepburn