North Middlesex is a municipality in Middlesex County, Ontario, Canada. The restructured municipality of North Middlesex was incorporated on January 1, 2001. This amalgamation joined five municipalities — the townships of East Williams, West Williams and McGillivray, the town of Parkhill and the village of Ailsa Craig — to form one municipal corporation. North Middlesex has a population of 6,658 as of the Canada 2011 Census.