Big Lake is a small rural city in Reagan County, Texas, United States. As of the 2010 Census, the city population was 2,936. It is the county seat of Reagan County.

Reagan County is a county on the Edwards Plateau in the U.S. state of Texas. As of the 2020 census, its population was 3,385. The county seat is Big Lake. The county is named after John Henninger Reagan (1818–1905), who was the postmaster general of the Confederate States and also a U.S. senator, U.S. representative, and first chairman of the Railroad Commission of Texas.