Hendrix, Joplin, SRV, VanZant.....way too many to think about. Lots of other performers besides singers too....Keith Moon & John Bonham were great drummers that expired too early IMO.
Otis Redding, Carla Thomas, Michael Jackson,Stevie Ray Vaughn,the Big Bopper,Richie Vallens,Buddy Holly,Jimmy Hendrix,Elvis Presley,John Lennon,Sam Cooke,You can tell I'm old but here's one that definitely had a great voice and greater demons..Amy Winehouse.