...comedian
...singer
...actor
...thinker
...athlete, oops never mind
Comedienne - Joan Rivers
Singer - Mel Blanc in "What's Opera Doc?"
Actor - The nominations are, Moe, Larry & Curly (honorable mention, Shemp). The winner is (obviously) Jerome "Curly" Howard/Horwitz, aka Curly Q. Link, aka the Missing Link!
Thinker - Albert Einstein
Athlete - Mark Spitz