King County is a county located in the U.S. state of Texas. The population was 265 at the 2020 census, making it the second-least populated county in Texas and the third-least populated county in the United States. King County has no incorporated communities. Its county seat is the census-designated place (CDP) of Guthrie. The county was created in 1876 and organized in 1891. It is named for William Philip King, who died at the Battle of the Alamo.

In 45 of the 50 states of the United States, the county is used for the level of local government immediately below the state itself. Louisiana uses parishes, and Alaska uses boroughs. In Connecticut, Massachusetts, and Rhode Island, some or all counties within states have no governments of their own; the counties continue to exist as legal entities, however, and are used by states for some administrative functions and by the United States Census bureau for statistical analysis. There are 3,242 counties and county equivalent administrative units in total, including the District of Columbia and 100 county-equivalents in the U.S. territories.