Personally, Bowie and Prince—because the entire fabric of the universe started breaking down after they died. For the third I'm torn between Donna Summer and Freddie Mercury, but ultimately I'd have to go with Mercury because as much as I loved Donna, I never felt her work was as good after she split with Giorgio Moroder.
bowie. bowie and bowie. Maybe Prince. 1983 Prince.
It seems I won a tic-tac-toe with Bowie/Petty/Lennon.
3 who were gone much too soon:
Prince, Jimi Hendrix, John Lennon