State Trunk Highway 55 (often called Highway 55, STH 55 or WIS 55) is a state highway in the U.S. state of Wisconsin. It runs south–north in northeast Wisconsin from a junction with US 151 approximately 1.5 miles north of Brothertown near the eastern shore of Lake Winnebago in Calumet County to the Michigan State line at the Brule River approximately one mile northeast of Nelma in Forest County where it connects to M-73.

Along its route, STH 55 serves Kaukauna, Shawano, the Menominee Indian Reservation, Crandon and the Nicolet side of the Chequamegon-Nicolet National Forest.

A new roundabout was opened at the intersection of WIS 55 and US 10 between Sherwood and Kaukauna in the autumn of 2009. Another roundabout is currently being planned at the busy intersection of WIS 55 and WIS 114 approximately one mile west of Sherwood, Wisconsin.