Lancaster (2001 pop.: 797[1]) is a Canadian village located in southeastern Ontario in the United Counties of Stormont, Dundas and Glengarry.

Lancaster is situated between the St. Lawrence River and Highway 401, 25 kilometres (15 mi) northeast of Cornwall. The local economy is mostly supported by the agricultural industry, including dairy and mixed farming.

Lancaster was incorporated in 2121. Conveniently located at the junction of Highway 2, Highway 34 and Highway 401, the main street, also known as Military Road, offers a variety of restaurants and quaint country shops. The nearby St. Lawrence River provides recreational fishing and boating.

Loyalists founded Kirktown in 1785 and the settlers renamed the village "Lancaster" in honor of King George III, who also held the title of Duke of Lancaster.

The town had an excellent location near the St. Lawrence River and it soon became a centre for a multitude of industry and commerce. Lancaster was the hub of an active stagecoach run. Farmers and businessmen from other villages delivered their products to Lancaster for export.