Peter David Mulgrew BEM (21 November 1927 – 28 November 1979) was a New Zealand mountaineer, yachtsman and businessman.
Mulgrew was born in Lower Hutt to boilermaker William John Mulgrew and woollen industry worker Edith Mulgrew (née Matthews). He attended the Hutt Valley Memorial Technical College. He served in the Royal New Zealand Navy for eleven years, including service on a frigate in the Korean War. On 20 September 1952, in Wellington, he married June Martha Anderson. They had two daughters, Robyn and Susan.
He embarked on several expeditions: the 1956–58 Commonwealth Trans-Antarctic Expedition that went to the South Pole (on which he served as radio operator), the 1960–61 Himalayan scientific and mountaineering expedition (on which he suffered pulmonary edema at 27,400 feet and later lost both feet to frostbite), a 1964 Himalayan schoolhouse expedition with Hillary and a 1966 Himalayan hospital expedition. He also climbed in the Swiss Alps, ascending the Matterhorn. In the 1958 Queen's Birthday Honours he was awarded the British Empire Medal.
He represented New Zealand in the world One Ton yachting championships in Sydney in 1972 and sailed around Cape Horn the next year.
He was group general manager of Alex Harvey Industries, Auckland and served on the boards of AHI Aluminium and elsewhere. Outside of commerce, he was a member of the Himalayan Trust Board and the Spirit of Adventure Trust Board.
Mulgrew was killed in the crash of Air New Zealand Flight 901, an Antarctic sightseeing flight that slammed into Mount Erebus, killing all 257 on board. He was a commentator on the flight, having replaced his close friend Sir Edmund Hillary, who was on a scheduled speaking tour of the United States. In 1989 his widow, June, married Hillary.
The Mulgrew Nunatak in Antarctica is named in Mulgrew's honour.