William James "Count" Basie (/ˈbeɪsi/; August 21, 1904 – April 26, 1984) was an American jazz pianist, organist, bandleader, and composer. In 1935, he formed the Count Basie Orchestra, and in 1936 took them to Chicago for a long engagement and their first recording. He led the group for almost 50 years, creating innovations like the use of two "split" tenor saxophones, emphasizing the rhythm section, riffing with a big band, using arrangers to broaden their sound, his minimalist piano style, and others.

Many musicians came to prominence under his direction, including the tenor saxophonists Lester Young and Herschel Evans, the guitarist Freddie Green, trumpeters Buck Clayton and Harry "Sweets" Edison, plunger trombonist Al Grey, and singers Jimmy Rushing, Helen Humes, Dennis Rowland, Thelma Carpenter, and Joe Williams.

As a composer, Basie is known for writing such jazz standards as "Blue and Sentimental", "Jumpin' at the Woodside" and "One O'Clock Jump".

William Basie was born to Lillian (Childs) and Harvey Lee Basie in Red Bank, New Jersey. His father worked as a coachman and caretaker for a wealthy judge. After automobiles replaced horses, his father became a groundskeeper and handyman for several wealthy families in the area. Both of his parents had some type of musical background. His father played the mellophone, and his mother played the piano; in fact, she gave Basie his first piano lessons. She took in laundry and baked cakes for sale for a living. She paid 25 cents a lesson for Count Basie's piano instruction.

The best student in school, Basie dreamed of a traveling life, inspired by touring carnivals which came to town. He finished junior high school, but spent much of his time at the Palace Theater in Red Bank, where doing occasional chores gained him free admission to performances. He quickly learned to improvise music appropriate to the acts and the silent movies.

Though a natural at the piano, Basie preferred drums. Discouraged by the obvious talents of Sonny Greer, who also lived in Red Bank and became Duke Ellington's drummer in 1919, Basie switched to piano exclusively at age 15. Greer and Basie played together in venues until Greer set out on his professional career. By then, Basie was playing with pickup groups for dances, resorts, and amateur shows, including Harry Richardson's "Kings of Syncopation". When not playing a gig, he hung out at the local pool hall with other musicians, where he picked up on upcoming play dates and gossip. He got some jobs in Asbury Park at the Jersey Shore, and played at the Hong Kong Inn until a better player took his place.

Around 1920, Basie went to Harlem, a hotbed of jazz, where he lived down the block from the Alhambra Theater. Early after his arrival, he bumped into Sonny Greer, who was by then the drummer for the Washingtonians, Duke Ellington's early band. Soon, Basie met many of the Harlem musicians who were "making the scene", including Willie "the Lion" Smith and James P. Johnson. One of his earliest gigs in Harlem was working in the band at Broadway Jones's nightclub; a job he was given by banjo player Elmer Snowden who had temporarily taken over leadership of the group while Jones was performing elsewhere.

Basie toured in several acts between 1925 and 1927, including Katie Krippen and Her Kiddies (featuring singer Katie Crippen) as part of the Hippity Hop show; on the Keith, the Columbia Burlesque, and the Theater Owners Booking Association (T.O.B.A.) vaudeville circuits; and as a soloist and accompanist to blues singer Gonzelle White as well as Crippen. His touring took him to Kansas City, St. Louis, New Orleans, and Chicago. Throughout his tours, Basie met many jazz musicians, including Louis Armstrong. Before he was 20 years old, he toured extensively on the Keith and TOBA vaudeville circuits as a solo pianist, accompanist, and music director for blues singers, dancers, and comedians. This provided an early training that was to prove significant in his later career.