Leon Russell, the longhaired, scratchy-voiced pianist, guitarist, songwriter and bandleader who moved from playing countless recording sessions to making hits on his own, died on Sunday in Nashville. He was 74.

His website said he had died in his sleep but gave no specific cause.

Mr. Russell’s health had incurred significant setbacks in recent years. In 2010, he underwent surgery for a brain fluid leak and was treated for heart failure. In July he had a heart attack and was scheduled for further surgery, according to a news release from the historical society of Oklahoma, his home state.

With his trademark top hat, hair well past his shoulders, a long, lush beard, an Oklahoma drawl and his fingers splashing two-fisted barrelhouse piano chords, Mr. Russell cut a flamboyant figure in the early 1970s. He led Joe Cocker’s band Mad Dogs & Englishmen, appeared at George Harrison’s 1971 Concert for Bangladesh in New York City and had numerous hits of his own, including “Tight Rope.”

Many of his songs became hits for others, among them “Superstar” (written with Bonnie Bramlett) for the Carpenters, “Delta Lady” for Mr. Cocker and “This Masquerade” for George Benson. More than 100 acts have recorded “A Song for You,” which Mr. Russell said he wrote in 10 minutes.