William Kennedy Fitzsimmons (31 January 1909 – 21 February 1992) was a Unionist politician in Northern Ireland. Born in Belfast, Fitzsimmons studied at and Belfast Technical College. He became a domestic engineer, and in 1948 was appointed as a Belfast Water Commissioner, serving as chairman of the Commissioners in 1954–55. In 1951, he became a justice of the peace. At the of 1973, Fitzsimmons served on the small Unionist team. Later in the year, he decided not to stand in the Northern Ireland Assembly election.