John Francis (Jack) O'Hagan (29 November 1898 – 15 July 1987) was an Australian musician.
O'Hagan was born in Fitzroy, Victoria, a suburb of Melbourne. He was the son of Pat O'Hagan, a hotelkeeper and Alice née Quinlan. He went to school at St Patrick's College and then later at Xavier College in Melbourne. His first job in the music business was at Allans Music in Melbourne - he played sheet music for potential customers. When radio was introduced to Australia, he was one of the first to broadcast for 3LO station.
Between 1916 and 1961 O'Hagan wrote over 600 songs, more than 200 of which were published. Some of O'Hagan's well-known songs are:
In the 1940s and 1950s, O'Hagan wrote many radio commercials and campfire songs. However, the combination of the rising popularity of rock and roll and television ended to his career.
Despite writing songs about the town O'Hagan first visited Gundagai in 1956 when he was guest of honour at the centenary celebrations of the town.
O'Hagan was awarded the Officer of the Order of the British Empire (OBE) in 1973.