Sir Rupert James "Dick" Hamer, AC, KCMG, ED (29 July 1916 – 23 March 2004) was an Australian politician who served as the 39th premier of Victoria from 1972 to 1981, and prior to that, the 18th deputy premier of Victoria from 1971 to 1972. He held office as the leader of the Victorian division of the Liberal Party of Australia (LPA) and a member of the Victorian Legislative Assembly (MLA) for the district of Kew.

Hamer was born in Melbourne to Elizabeth Anne McLuckie and Hubert Hamer, a solicitor. His three siblings all achieved success in their fields: his sister was Alison Patrick (1921–2009), an internationally known historian of the French Revolution; his brothers were David Hamer (1923–2002), a federal Liberal politician, and Alan, a Rhodes Scholar, chemist and managing director of ICI Australia.

Hamer was educated at Melbourne Grammar School and Geelong Grammar School and graduated in law from the University of Melbourne, where he was resident at Trinity College from 1936. He was a member, with his brother Alan, of the College First XVIII Australian Rules football team, and was Secretary of the Student Club. He joined the Melbourne University Regiment of the Australian Army in 1935 and served with them until 1939. He was commissioned as an officer in August 1940 in 2nd/43rd Battalion AIF and served at Tobruk, Syria, El Alamein, New Guinea and in Normandy. He was Mentioned in Dispatches in 1945 for "distinguished service in the South-West Pacific". After the war he became a partner in his family's law firm and was active in the Liberal Party. In 1944 he married April Mackintosh, with whom he had five children. He continued his military service and remained active in the Citizens Military Force joining the Victorian Scottish Regiment in 1948, of which he was Commanding Officer from 1954 to 1958.

Hamer was elected to the Victorian Legislative Council for East Yarra Province in 1958. He was appointed to the cabinet of the Premier, Henry Bolte, in 1962, becoming Assistant Chief Secretary. He was Minister for Local Government from 1964 to 1971.

After Deputy Premier Arthur Rylah's retirement, Hamer was elected in a by-election for Rylah's Legislative Assembly seat of Kew in eastern Melbourne. He immediately assumed Rylah's portfolios of Deputy Premier and Chief Secretary. Although he was loyal to Bolte, he had a reputation for being much more liberal than his rough-edged conservative leader.

By the 1970s, the Liberal government was losing its appeal to younger, urban voters in Melbourne. Realizing that the Liberals had a year at most to retool their image before a statutory general election, Bolte retired in 1972 and endorsed Hamer as his successor. Despite opposition from the conservative wing of the party, Bolte's support was enough for Hamer to prevail in the ensuing leadership ballot, and he was sworn in as premier on 23 August.

Hamer represented such a sharp change from the Bolte era that he was able to campaign in the 1973 election as a new, reformist leader, despite the fact that the Liberals had been in power for 18 years. Employing the slogan "Hamer Makes It Happen", he won a landslide against the Labor opposition under Clyde Holding, increasing his party's already large majority. He won an even larger victory in 1976, defeating Holding yet again.

Hamer, assisted by key allies such as Planning Minister Alan Hunt, Conservation Minister Bill Borthwick, Attorney-General Haddon Storey, Social Welfare Minister Vasey Houghton, Housing and Youth Sport and Recreation Minister Brian Dixon and Community Welfare Services Minister Walter Jona moved to modernise and liberalise government in Victoria. Environmental protection laws were greatly strengthened, the death penalty was abolished, Aboriginal communities were given ownership of their lands, abortion and homosexuality were decriminalised and anti-discrimination laws were introduced.