Herndon is a city in Rawlins County, Kansas, United States. As of the 2010 census, the city population was 129.
Herndon is located at 39°54′34″N 100°47′10″W / 39.90944°N 100.78611°W / 39.90944; -100.78611 (39.909468, -100.786094). According to the United States Census Bureau, the city has a total area of 0.3 square miles (0.7 km²), all of it land.
As of the census of 2000, there were 149 people, 83 households, and 37 families residing in the city. The population density was 561.1 people per square mile (213.1/km²). There were 107 housing units at an average density of 402.9 per square mile (153.0/km²). The racial makeup of the city was 99.33% White, and 0.67% from two or more races.