Lester William Polsfuss (June 9, 1915 – August 12, 2009), known as Les Paul, was an American jazz, country, and blues guitarist, songwriter, luthier, and inventor. He was one of the pioneers of the solid-body electric guitar, and his prototype, called the Log, served as inspiration for the Gibson Les Paul. Paul taught himself how to play guitar, and while he is mainly known for jazz and popular music, he had an early career in country music. In the 1950s, he and his wife, singer and guitarist Mary Ford, made numerous recordings, selling millions of copies.

Paul is credited with many recording innovations. His early experiments with overdubbing (also known as sound on sound), delay effects such as tape delay, phasing, and multitrack recording were among the first to attract widespread attention. His licks, trills, chording sequences, fretting techniques, and timing set him apart from his contemporaries and inspired many guitarists of the present day.

Among his many honors, Paul is one of a handful of artists with a permanent exhibit in the Rock and Roll Hall of Fame. He is prominently named by the music museum on its website as an "architect" and a "key inductee" with Sam Phillips and Alan Freed. Paul is the only inductee in both the Rock and Roll Hall of Fame and the National Inventors Hall of Fame.

Paul was born Lester William Polsfuss in Waukesha, Wisconsin, to George and Evelyn (Stutz) Polsfuss, both of German ancestry. Paul's mother was related to the founders of Milwaukee's Valentin Blatz Brewing Company, and to the makers of Stutz automobiles. His parents divorced when he was a child. His mother simplified their Prussian family name first to Polfuss, then to Polfus, although Les Paul never legally changed his name. Before taking the stage name Les Paul, he performed as Red Hot Red and Rhubarb Red.

At the age of eight, Paul began playing the harmonica. After learning the piano, he switched to the banjo and guitar. During this time, Paul invented a neck-worn harmonica holder that allowed hands-free switching from one side of a double-sided harmonica to the other. His design is still widely manufactured today. By age thirteen, Paul was performing semi-professionally as a country-music singer, guitarist, and harmonica player. While playing at Waukesha-area drive-ins and roadhouses, Paul made his first experiments in attaching electric amplification directly to instruments (as opposed to playing them near a microphone) and in modifying the instruments themselves. Wanting to make his acoustic guitar heard by more people at local venues, he wired a phonograph needle to his guitar and connected it to a radio speaker. As a teen Paul experimented with sustain effects, and built a guitar-like instrument using a 2-foot piece of rail from a nearby train line as the body. At age seventeen, Paul played with Rube Tronson's Texas Cowboys, and soon after that he dropped out of high school to team up with Sunny Joe Wolverton's Radio Band in St. Louis, Missouri, who played regularly on KMOX.

Paul and Wolverton moved to Chicago in 1934, where they continued to perform country music on radio station WBBM and at the 1934 Chicago World's Fair. While in Chicago, Paul learned jazz from the great performers on Chicago's Southside. During the day, he played country music as Rhubarb Red on the radio. At night, he was Les Paul, playing jazz. He met pianist Art Tatum, whose playing influenced him to continue with the guitar rather than play jazz on the piano. His first two records were released in 1936, credited to "Rhubarb Red", Paul's hillbilly alter ego. He also served as an accompanist for other bands signed to Decca. During this time, he began adding different sounds and adopted his stage name of Les Paul.

Paul's guitar style was strongly influenced by the music of Django Reinhardt, whom he greatly admired. Following World War II, Paul sought out and made friends with Reinhardt. When Reinhardt died in 1953, Paul paid for part of the funeral's cost. One of Paul's prized possessions was a Selmer acoustic guitar given to him by Reinhardt's widow.

Paul formed a trio in 1937 with rhythm guitarist Jim Atkins (older half-brother of guitarist Chet Atkins) and bassist/percussionist Ernie "Darius" Newton. They left Chicago for New York in 1938, landing a featured spot with Fred Waring's radio show. Chet Atkins later wrote that his brother, home on a family visit, presented him with an expensive Gibson archtop guitar that Les Paul had given to Jim. Chet recalled that it was the first professional-quality instrument he ever owned.