Madill is a city in Marshall County, Oklahoma, United States. The city was founded in 1901 and is named for George Alexander Madill, an attorney for the St. Louis-San Francisco Railway, popularly known as the Frisco. The 2009 population estimate was 3,781. It is the county seat of Marshall County.
Madill is located at 34°5′29″N 96°46′25″W / 34.09139°N 96.77361°W / 34.09139; -96.77361 (34.091261, -96.773565).
According to the United States Census Bureau, the city has a total area of 2.9 square miles (7.6 km²), of which, 2.9 square miles (7.5 km²) of it is land and 0.04 square miles (0.1 km²) of it (1.37%) is water.