Donald Dean Summerville (4 August 1915 – 19 November 1963) was a Canadian politician who served as the 53rd mayor of Toronto from January 1963 until his death that same year.

Before public office he was manager of family owned real estate company Summerville Properties (founded 1912).

[6] He was first elected to city council in 1955 as the alderman for Ward 8, in east-end Toronto, that included The Beaches neighbourhood.

On 19 November 1963, Summerville suffered a fatal heart attack while playing in a charity hockey game at the George Bell Arena in the west-end Toronto neighbourhood known as The Junction.

[8] The inquiry into the emergency response to his death found that the closest ambulance was not sent because its service did not have jurisdiction over The Junction and so was not called.