Proper noun
(Australia, obsolete) Imaginary king of the Australian aboriginal people.
Tasmanian aboriginal man William Lanne (c.1835-1869) believed to have been the last Tasmanian aboriginal man.
Any one of various other aboriginal men at times referred to as King Billy.
(Ireland, Scotland, informal) King William III of England.
Source: en.wiktionary.orgHull has a number of historical statues such as the Wilberforce Memorial in Queen's Gardens and the gilded King William III statue on Market Place (known locally as "King Billy"). Source: Internet