Fillmore is a city and the county seat of Millard County, Utah, United States. The population was 2,592 at the 2020 United States Census. It is named for the thirteenth U.S. President Millard Fillmore, who was in office when Millard County was created by the Utah Territorial legislature. Fillmore was the capital of the Utah Territory from 1851 to 1856, although the territorial legislature met in Fillmore only one term. The original Utah Territorial Statehouse building still stands.