Allen County is a county located in the U.S. state of Kentucky. As of the 2020 census, the population was 20,588. Its county seat and only municipality is Scottsville. The county is named for Colonel John Allen, a state senator and soldier who was killed leading the 1st Regiment of Kentucky Rifleman at the Battle of Frenchtown, Michigan during the War of 1812. Allen County was a dry county until 2023, when it voted to legalize the sale of alcohol.