John Leahy, English lawyer and diplomat, High Commissioner to Australia (born 1928)

Sir John Henry Gladstone Leahy, was a senior British diplomat. He was Ambassador to South Africa from 1979 to 1982, and High Commissioner to Australia from 1984 to 1988. He later became Chairman of Lonrho.

The high commissioner of the United Kingdom to Australia is an officer of the Foreign, Commonwealth and Development Office and the United Kingdom's foremost diplomatic representative to the Commonwealth of Australia. Despite Britain's close relationship with Australia, the first high commissioner from London was not appointed until 1936, owing to the clarification of Britain's relations with the imperial dominions after the Statute of Westminster 1931.