Lionel Bart (1 August 1930 – 3 April 1999) was an English writer and composer of pop music and musicals. He wrote Tommy Steele's "Rock with the Caveman" and was the sole creator of the musical Oliver! (1960). With Oliver! and his work alongside theatre director Joan Littlewood at Theatre Royal, Stratford East, he played an instrumental role in the 1960s birth of the British musical theatre scene after an era when American musicals had dominated the West End.

Best known for creating the book, music and lyrics for Oliver!, Bart was described by Andrew Lloyd Webber as "the father of the modern British musical". In 1963 he won the Tony Award for Best Original Score for Oliver!, and the 1968 film version of the musical won a total of 6 Academy Awards including the Academy Award for Best Picture.

Some of his other songs include the theme song to the James Bond film From Russia with Love, and the songs "Living Doll" by Cliff Richard, "Far Away" by Shirley Bassey, "Do You Mind?" (recorded by both Anthony Newley and Andy Williams), "Big Time" (a 1961 cover by Jack Jones of his show tune from Fings Ain't Wot They Used T'Be), "Easy Going Me" by Adam Faith, "Always You And Me" by Russ Conway, and several songs recorded by Tommy Steele ("A Handful of Songs", "Butterfingers" and "Little White Bull"). By the mid 1960s he was as well known for his outlandish lifestyle, his celebrity friends, his excesses and his parties, as he was for his work.