Potwin is a city in Butler County, Kansas, United States. It is named after the town site land owner Charles Potwin. As of the 2020 census, the population of the city was 421.

Butler County is a county in the U.S. state of Kansas and is the largest county in the state by total area. Its county seat is El Dorado and its most populous city is Andover. As of the 2020 census, the county population was 67,380. The county was named for Andrew Butler, a U.S. Senator from South Carolina who coauthored the Kansas–Nebraska Act.