Fort William was a city in Ontario, Canada, located on the Kaministiquia River, at its entrance to Lake Superior. It amalgamated with Port Arthur and the townships of Neebing and McIntyre to form the city of Thunder Bay in January 1970. Since then, it has been the largest city in Northwestern Ontario. The city's Latin motto was A posse ad esse, featured on its coat of arms designed in 1900 by town officials, "On one side of the shield stands an Indian dressed in the paint and feathers of the early days; on the other side is a French voyageur; the cent[re] contains a grain elevator, a steamship and a locomotive, while the beaver surmounts the whole."

The Kaministiquia River is a river which flows into western Lake Superior at the city of Thunder Bay, Ontario. Kaministiquia is an Ojibwe word meaning "where a stream flows in island" due to two large islands at the mouth of the river. The delta has three branches or outlets, reflected on early North American maps in French as "les trois rivières" : the southernmost is known as the Mission River, the central branch as the McKellar River, and the northernmost branch as the Kaministiquia. Residents of the region commonly refer to the river as the Kam River.