Douglas Mary McKain (20 July 1789 – 3 April 1873) was a New Zealand nurse, midwife and businesswoman.
She was born Douglas Mary Dunsmore in Glasgow, Lanarkshire, Scotland on 20 July 1789 and died 3 April 1873 in Napier.
She arrived in New Zealand as a widow, accompanied by four sons and a daughter, on the ship Olympus, which arrived in Port Nicholson (Wellington) in April 1841.