Gray, who had cancer, died Tuesday at his Nashville home, said Charlie Andrews, his attorney.
The silky-voiced tenor was best known for his progressive rock and soul version of "Drift Away," a 1973 top 5 hit penned by Mentor Williams that includes the lyric, "I wanna get lost in your rock and roll and drift away." It remains a staple of oldies radio.
A subsequent recording by Gray, "Loving Arms," was frequently covered by singers from rock, country and R&B.
"I guess what you call my 'signature songs' will never die, thank God," Gray told the Tennessean newspaper in 1988.
When Gray was featured on a 2003 version of "Drift Away" by rap artist Uncle Kracker, the song once again became a hit.
Gray "had such a unique style, so identifiable," said Bud Reneau, his songwriting partner. "It was a big factor in his marketability."
He was born July 26, 1940, in Simonton, Texas, into a family of sharecroppers. References list his given name as Leonard Victor Ainsworth or Laurence Darrow Brown, according to the All Music Internet database.
After moving to California in the early 1960s, Gray appeared in a Los Angeles production of the musical "Hair" and recorded his first chart hit, "Look at Me," after encountering Sonny Bono, then an executive at Specialty Records.
Later, Gray toured extensively in Europe, Australia and Africa and insisted on performing for integrated audiences in South Africa, according to All Music.
In the 1970s, Gray moved to Nashville and worked increasingly as a songwriter, mainly in a country vein. His compositions were covered by such artists as Ray Charles, Johnny Mathis, Etta James, Three Dog Night and John Denver.
Gray, who was not married and had no children, willed much of his property and future earnings to St. Jude Children's Research Hospital in Memphis, Tenn., Reneau said.