Gerald Joseph Monaghan (February 27, 1915 – June 2, 1973) was a Canadian politician, who represented the electoral district of Sudbury in the Legislative Assembly of Ontario from 1955 until 1959. He was a member of the Ontario Progressive Conservative Party. He was born in Thurso, Quebec in 1915. Prior to his election to the legislature, Monaghan was a city councillor in Sudbury. He died in 1973.