Johnny St. Cyr (April 17, 1890 – June 17, 1966) was an American jazz banjoist and guitarist. For banjo his by far most used type in records at least was the six string one. On a famous “action photo” with Jelly Roll Morton’s Red Hot Peppers he is holding a four string banjo, probably tenor. There is, however, no verified information if he ever used such an instrument on records.

St. Cyr was born in New Orleans, Louisiana and raised Catholic. He played for several leading New Orleans bands before moving to Chicago in 1923. He is best remembered as a member of Louis Armstrong's Hot Five and Hot Seven bands. He also played with Jelly Roll Morton's Red Hot Peppers. He composed the standard "Oriental Strut", known for its adventurous chord sequence.

During the 1950s, he performed and led a group named Johnny St. Cyr and His Hot Five and recorded with Paul Barbarin and George Lewis. From 1961 until his death in 1966, St. Cyr was the bandleader of the Young Men from New Orleans, who performed at Disneyland. He died in Los Angeles, California, and is buried in Evergreen Cemetery, in Los Angeles.