Orson Welles IS...
Mean Mr. Mustard from the Sgt. Pepper's movie
Welles also would have been perfect as either Marvin Sunk, The Sun King (played in the actual film by Alice Cooper) or in Donald Pleasence's spot as reord sleaze merchant B.D. Brockhurst, which would have given the world the Orson Welles/Stargard musical number it never knew it needed.
Kenny Rogers' role in "Six Pack." A county singing racecar driver being hectored by Erin Grey and a whole mess of children.
For two hours.
This might be the best answer. All due respect to the legendary Kenny Rogers, but the dialogue below was meant to be delivered by Orson Welles:
Brewster Baker: He's right, Swifty. Be polite, Mr. Logan here's a very sensitive man.
[takes a few steps away and looks at Terk]
Brewster Baker: On second thought, I got a good mind to turn this little kid loose and let him just whip your ass, Terk!