William Douglas Cook (New Plymouth, New Zealand, 28 October 1884 – Gisborne, New Zealand, 27 April 1967) was the founder of Eastwoodhill Arboretum, now the national arboretum of New Zealand, and one of the founders of Pukeiti, a rhododendron garden, close to New Plymouth. He was a "plantsman with the soul of a poet and the vision of a philosopher".