Ian "Stu" Stewart was one of the most important figures in the Rolling Stones' early days, and yet he's often overlooked in most discussions about the band. He served double duty, often unseen, as both their piano player and road manager, eventually becoming known in their camp as the "Sixth Stone."

Born on July 18, 1938, "Stu" fell in love with American jazz and blues like so many other British kids, and took up both piano and banjo. In May 1962, he answered an ad placed by Brian Jones looking for musicians, and was soon joined by the other future members of the Stones. But when Andrew Loog Oldham began managing the band, he fired Stu because his looks didn't fit the rebellious image he was chasing for the Stones. Instead, he asked Stewart, who was a few years older and more disciplined than the others, to be the road manager.

"I'm still working for him," Keith Richards said of Stewart in his autobiography Life. "To me, the Rolling Stones is his band. Without his knowledge and organization, without the leap he made from where he was coming from, to take a chance on playing with a bunch of kids, we'd be nowhere."

Even though he was no longer a performing member of the band he affectionately referred to as his "little three-chord wonders," Stu still wound up on almost every Stones album made in his lifetime. (The exceptions were Beggars Banquet and Their Satanic Majesties Request.) His playing can be heard on such tracks as "Time Is on My Side," "Honky Tonk Women," "Brown Sugar" and "It's Only Rock 'N Roll," and he frequently joined the group onstage from 1969 to 1982. He also played on Led Zeppelin's "Rock and Roll" and "Boogie With Stu," which was named in his honor.

Despite eschewing many aspects of the rock 'n' roll lifestyle, Stewart died young, suffering a fatal heart attack on Dec. 12, 1985, at the age of 47. Stu's contributions were so important, however, that the Rolling Stones insisted that he join them as a posthumous inductee into the Rock & Roll Hall of Fame in 1989.

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