Clasen (February 10, 1829 – September 29, 1907) was an American businessman and politician.
Born in Mecklenberg-Schwerin, Germany, Clasen went to Quebec, Canada and then went to Milwaukee, Wisconsin.
He then settled in Brookfield, Wisconsin where he operated a sawmill, a farm, and a store.
He served as postmaster.
In 1874, Clasen served in the Wisconsin State Assembly and was a Democrat.
He also served as county treasurer for Waukesha County, Wisconsin.