William Douglas Cook, New Zealand horticulturalist, founded Eastwoodhill Arboretum (died 1967)

William Douglas Cook 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".

Eastwoodhill is the national arboretum of New Zealand. It covers 131 hectares (1.31 km²) and is located 35 km northwest of Gisborne, in the hill country of Ngatapa. It was founded in 1910 by William Douglas Cook. Cook's life work would become the creation of a giant collection of Northern Hemisphere temperate climate zone trees in New Zealand – a dream that would eventually cost him all his money – buying and importing thousands of trees from New Zealand and British nurseries.