GENIUSES:
 

Well, they sure as hell aren't/ weren't "stupid..."
 

It'll be a while before I think of all of those who should go here, but here goes:

Einstein (duh)
Werner Von Braun
Oppenheimer
Benjamin Franklin
Homer Hickam, Jr.  (see the movie "October Sky")

FICTICIOUS:

Mr Spock
Sherlock Holmes
Moe Howard  (haha)

REAL PEOPLE:

Musicians - composing and arranging, mostly - but musicianship, too

John Miles   (his mid 70s "Rebel" is his best work, I think)
Steven Tyler
Mike Oldfield
John Lennon
George Harrison
David Bowie
Alice Cooper
Keith Emerson
Rick Wakeman
Jon Anderson
Steve Howe
Bill Bruford
Trevor Rabin
Freddie Mercury
Carlos Santana
Neil Schon