Harold Edward Holt, CH (5 August 1908 – 17 December 1967) is an Australian politician and the 17th Prime Minister of Australia.

Holt spends 32 years in Parliament, including many years as a senior Cabinet Minister, but is Prime Minister for only 22 months.

This abbreviated term necessarily limits his personal and political impact, especially when compared to his immediate predecessor Sir Robert Menzies, who was Prime Minister for a total of 18 years.

As Minister for Immigration (1949–1956), Holt is responsible for the relaxation of the White Australia policy and as Treasurer under Menzies, he initiates major fiscal reforms including the establishment of the Reserve Bank of Australia, and launches and guides the process to convert Australia to decimal currency.

As Prime Minister, he oversees landmark changes including the historic decision not to devalue the Australian dollar in line with the British pound, and the 1967 constitutional referendum in which an overwhelming majority of Australians vote in favor of giving the Commonwealth power to legislate specifically for indigenous Australians.

His term as Prime Minister is brought to an early end in December 1967 when he disappears while swimming at Cheviot Beach near Portsea, Victoria, and is presumed drowned.

Today, Holt is mainly remembered for his somewhat controversial role in expanding Australia's involvement in the Vietnam War; for his famous "All the way with LBJ" quote; and for the sensational circumstances of his death.

In the opinion of his biographer Tom Frame, these have tended to obscure the many achievements of Holt's long and distinguished political career.