William Delafield Cook AM (1936–2015) was an Australian artist who was known for his photorealistic landscapes. He won a number of awards, including the Order of Australia.

Delafield Cook was born in Melbourne, Australia on 28 February 1936. His grandfather, who was also named William Delafield Cook, was also a painter and had links to the Heidelberg School of Australian painting.

In 1962 he married 1962 Sally Patricia Bovington, with whom he had two daughters, and a son, the artist Jonathan Delafield Cook.

In 1980 Delafield Cook won the Wynne Prize for A Waterfall (Strath Creek), and in 1981 he won the Sulman Prize for A French family.

Delafield Cook taught at the University of Melbourne.

In 2013 Delafield Cook was appointed a Member of the Order of Australia for "significant service to the visual arts as a realist painter of Australian landscapes".

Delafield Cook died after a brief illness in London on 29 March 2015, where he had been preparing for an exhibition; he was aged 79. He had long divided his time between London and Melbourne.

Critic John McDonald, in his Art and Australia review of Deborah Hart's monograph on the artist, remarks on: