Leonard "Lenny" Hart (1918/19–1974) was a drummer, who owned and operated Hart Music, selling drums and musical instruments in San Carlos, California. He was the father of Mickey Hart, one of the percussionists for the Grateful Dead. Lenny Hart was also the Grateful Dead's original money manager. Lenny Hart was responsible for disappearing with a large sum of the group's profits (approx. US$155,000) in March, 1970. Later that same month, the Grateful Dead recorded Workingman's Dead and toured Canada by train as part of the Trans Continental Pop Festival, which was later depicted in the documentary, Festival Express.
Lenny Hart was arrested in San Diego in the summer of 1971, while baptizing people and using the name "Rev. Lenny B. Hart." 
The Grateful Dead song "He's Gone" is based on Lenny Hart's embezzlement of band money and subsequent disappearance. As a result of the fiasco, Mickey Hart left the band in February 1971, not returning to the group on a full-time basis until 1974.
- Rolling Stone, 2 September 1971
- Relix, vol. 5, #2, p. 24