William Blue (c. 1767 – 7 May 1834) was an Australian convict who, after completing his sentence, became a boatman providing one of the first services to take people across Sydney Harbour. He was also made a water bailiff and watched boat traffic on Port Jackson from a special tower. Although Billy Blue's place and date of birth are uncertain, convict records suggest he was born in Jamaica, New York, around 1740 or 1767. Other people reading his records believe him to have been from Jamaica, West Indies.