John Francis "Jack" O'Hagan OBE (29 November 1898 – 15 July 1987) was an Australian singer-songwriter and radio personality.O'Hagan was born as John Francis O'Hagan, in Fitzroy, 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.