Sullivan (formerly Winfield) is a village in Jefferson County, Wisconsin, United States. The population was 688 at the 2000 census. The village is located within the Town of Sullivan, and is known to residents of Southern Wisconsin including the Madison and Milwaukee metro areas as the location of the National Weather Service forecast office MKX.
Sullivan is located at 43°0′46″N 88°35′15″W / 43.01278°N 88.5875°W / 43.01278; -88.5875 (43.012791, -88.587515). It is located about 30 miles west of Milwaukee and 40 miles east of Madison, approximately 6 miles south of Interstate 94. The center of the village is situated at the intersection of Main Street (Hwy 18 and Hwy F) and Palmyra Street (Hwy E).
According to the United States Census Bureau, the village has a total area of 1.1 square miles (2.9 km²), all of it land.