Jack Marshall, New Zealand colonel, lawyer and politician, 28th Prime Minister of New Zealand (b. 1912)
Sir John Ross Marshall (5 March 1912 – 30 August 1988) was a New Zealand politician of the National Party. He entered Parliament in 1946 and was first promoted to Cabinet in 1951. After spending twelve years as the deputy prime minister of New Zealand, he served as the 28th prime minister from February until December 1972.

The Second National Government, in office since 1960, appeared worn-out and out of touch, and at the time of Marshall's appointment it seemed headed for heavy electoral defeat. After Labour's victory in the 1972 general election, Marshall became Leader of the Opposition. He was determined to remain as leader of the National Party, but in July 1974 was challenged for the leadership by Robert Muldoon, his deputy, rival and successor.

Marshall's politeness and courtesy were well known, and he was sometimes nicknamed Gentleman Jack. He disliked the aggressive style of some politicians, preferring a calmer, less confrontational approach. These traits were sometimes misinterpreted as weakness by his opponents. Marshall was a strong believer in pragmatism, and he disliked what he considered populism in other politicians of his day. At his death he was described as "A soft spoken lawyer almost too nice to be a politician".