William Henry McGuire (May 31, 1873 – October 31, 1957) was a Canadian senator who represented East York for 30 years.
He attended high school in Campbellford, Ontario, and was assisted in attaining higher education by an older brother, Father Michael McGuire, who was a Roman Catholic priest in the area.
William "Billy" McGuire graduated from the University of Toronto in 1903 and studied law at Osgoode Hall.
He was named to the Senate of Canada by Prime Minister William Lyon Mackenzie King on December 20, 1926 and served East York until his death on October 31, 1957, an impressive total of 30 years, 10 months and 12 days.
He and Senator Frank Patrick O'Connor (Scarborough Junction) acquired a vacant church in the village of Wexford (Lawrence Avenue East, east of Victoria Park Avenue, now in the Scarborough area of Toronto) to establish Precious Blood parish.