Robert Johnson
Robert Johnson was an influential blues singer, guitarist, and and song writer. He died in August 1938, possibly poisoned by his girlfriend's husband. According to legend, he made a deal with the devil to become a great blues musician.
Brian Jones
Brian Jones, guitarist and the original leader of The Rolling Stones, drowned in a swimming pool in July 1969. He was widely known to have had a substance abuse problem.
Jimi Hendrix
Jimi Hendrix died in September, 1970, chocking on his own vomit, after taking a strong sleeping pill. There is an unproven rumor that he was murdered by his manager. Jimi is widely considered to be the greatest electric guitar player who ever lived.
Janis Joplin
Janis Joplin died a month after Jimi Hendrix in October 1970. She was one of the greatest women blues and rock singers of all time. She died of a heroin overdose.
Jim Morrison
Jim Morrison, poet and lead singer of The Doors, died in July, 1971. His death may have been due to a heroin overdose, but the exact cause remains unknown. He died in Paris and is buried in Pere Lachaise Cemetery there.
Kurt Cobain
Kurt Cobain, a heroin addict, committed suicide in April 1994. He was the lead singer and guitarist of Nirvana.
In addition to these giants of rock music, there is a long list of lesser-known musicians who died at age 27. These include Rudy Lewis of The Drifters (overdose), Alan Wilson of Canned Heat (possible suicide), Kristen Pfaff of Hole and Janitor Joe (overdose), and the rappers Stretch, Fat Cat, and Freaky Tah (murdered).
Rest in Peace.