Thelonious Sphere Monk (October 10, 1917 – February 17, 1982) was an American jazz pianist and composer, considered one of the giants of American music. Monk had a unique improvisational style and made numerous contributions to the standard jazz repertoire, including "'Round Midnight," "Blue Monk," "Straight, No Chaser" "Ruby, My Dear," "Epistrophy," and "Well, You Needn't". Monk is the second-most recorded jazz composer after Duke Ellington, which is particularly remarkable as Ellington composed more than 1,000 pieces, whereas Monk wrote about 70.

His compositions and improvisations feature dissonances and angular melodic twists, and are consistent with Monk's unorthodox approach to the piano, which combined a highly percussive attack with abrupt, dramatic use of silences and hesitations. This style was not universally appreciated, shown for instance in poet and jazz critic Philip Larkin's dismissal of Monk as "the elephant on the keyboard".