Thayer County is a county in the U.S. state of Nebraska. As of the 2020 United States Census, the population was 5,034. Its county seat is Hebron. The county was created in 1856 and originally named Jefferson County. It was organized in 1870-1871 and renamed for General and Governor John Milton Thayer.

Hebron is a city in and the county seat of Thayer County, Nebraska, United States. The population was 1,441 at the 2020 census.