The Beaver Wars were a series of conflicts fought intermittently during the 17th century in North America throughout the Saint Lawrence River valley in Canada and the lower Great Lakes region which pitted the Iroquois against the Hurons, northern Algonquians and their French allies.

The Iroquois sought to expand their territory and to monopolize the fur trade with European markets. The Iroquois Confederation led by the Mohawks mobilized against the largely Algonquian-speaking tribes and Iroquoian-speaking Huron and related tribes of the Great Lakes region. The Iroquois were supplied with arms by their Dutch and English trading partners; the Algonquians and Hurons were backed by the French, their chief trading partner.

The Iroquois effectively destroyed several large tribal confederacies, including the Mohicans, Huron (Wyandot), Neutral, Erie, Susquehannock (Conestoga), and northern Algonquins, with the extreme brutality and exterminatory nature of the mode of warfare practised by the Iroquois causing some historians to label these wars as acts of genocide committed by the Iroquois Confederacy. They became dominant in the region and enlarged their territory, realigning the American tribal geography. The Iroquois gained control of the New England frontier and Ohio River valley lands as hunting ground from about 1670 onward.

The wars and subsequent commercial trapping of beavers was devastating to the local beaver population. Trapping continued to spread across North America, extirpating or severely reducing populations across the continent. The natural ecosystems that came to rely on the beavers for dams, water and other vital needs were also devastated leading to ecological destruction, environmental change, and drought in certain areas. Beaver populations in North America would take centuries to recover in some areas, while others would never recover.