Stephen Stills (born January 3, 1945)is an American singer, songwriter, and multi-instrumentalist best known for his work with Buffalo Springfield and Crosby, Stills, Nash & Young. As both a solo act and member of two successful bands, Stills has combined record sales of over 35 million albums. He was ranked number 28 in Rolling Stone's 2003 list of "The 100 Greatest Guitarists of All Time" and number 47 in the 2011 list.Stills became the first person to be inducted twice on the same night into the Rock and Roll Hall of Fame. According to Neil Young, "Stephen is a genius."

Beginning his professional career with Buffalo Springfield, he composed "For What It's Worth", which became one of the most recognizable songs of the 1960s. Other notable songs he contributed to the band were "Sit Down, I Think I Love You", "Bluebird", and "Rock & Roll Woman". According to bandmate Richie Furay, he was "the heart and soul of Buffalo Springfield".

After Buffalo Springfield disbanded, Stills began working with David Crosby and Graham Nash as a trio called Crosby, Stills & Nash (CSN). In addition to writing many of the band's songs, Stills played bass, guitar, and keyboards on their debut album. The album sold over four million copies and at that point had outsold anything from the three members' prior bands: the Byrds, Buffalo Springfield, and the Hollies. The album won the trio a Grammy Award for Best New Artist.