Birnamwood is a village in Marathon and Shawano Counties in the U.S. state of Wisconsin. It is part of the Wausau, Wisconsin Metropolitan Statistical Area. The population was 795 at the 2000 census. The village is located mostly within the Town of Birnamwood in Shawano County; only a small portion extends into the Town of Norrie in adjacent Marathon County. Until the 1990s, Birnamwood was home to the world's largest fiberglass badger. U.S. Route 45 runs through the village.