William Morris "Billy" Hughes, CH, KC, (25 September 1862 – 28 October 1952), Australian politician, is the seventh Prime Minister of Australia, from 1915 to 1923.

Over the course of his 51-year federal parliamentary career (and an additional seven years prior to that in a colonial parliament), Hughes changes parties five times: from Labor (1901–16) to National Labor (1916–17) to Nationalist (1917–30) to Australian (1930–31) to United Australia (1931–44) to Liberal (1944–52).

He is expelled from three parties, and represents four different electorates in two states.

Originally Prime Minister as leader of the Labor Party, his support of conscription leads him, along with 24 other pro-conscription members, to form National Labor.

National Labor merges with the Commonwealth Liberal Party to form the Nationalist Party.

His prime ministership comes to an end when the Nationalist party is forced to form a coalition with the Country Party, whose members refuse to serve under Hughes.

He is the longest serving prime minister up to this point, and the fifth longest serving over all.

He will later lead the United Australia Party to the 1943 election, though Arthur Fadden serves as Coalition leader.

He dies in 1952 at age 90, while still serving in Parliament.

He is the longest-serving member of the Australian Parliament, and one of the most colorful and controversial figures in Australian political history.