Thelonious Monk (1917–1982) was an American jazz pianist and composer renowned for his unique improvisational style and significant contributions to the standard jazz repertoire. His compositions, including "'Round Midnight," "Blue Monk," "Straight, No Chaser," "Ruby, My Dear," "In Walked Bud," and "Well, You Needn't," have become jazz standards. Monk's music is characterized by dissonances and angular melodic twists, often incorporating unexpected chromatic notes and a highly percussive attack. He was a pivotal figure in the development of bebop and remains the second-most-recorded jazz composer after Duke Ellington.