Cromwell is a town in Seminole County, Oklahoma, United States. The population was 265 at the 2000 census.
Cromwell was a wild and wooly town in the early 1920s. The town was said to be full of saloons, brothels and outlaws. On Halloween night, 1924, Cromwell Town Marshal and legendary Old West lawman Bill Tilghman was shot outside of a cafe called "Ma Murphy's", by a corrupt prohibition agent named Wiley Lynn. Tilghman died in the early morning hours of the first of November. Tilghman had been brought in to help bring the town under control. One month later the town of Cromwell was torched, with every brothel, bar, flop house and pool hall allegedly having been burned to the ground by friends of Tilghman. There was no investigation into the massive fire, and Cromwell never recovered its former wild status.
Cromwell is located at 35°21′1″N 96°27′35″W / 35.35028°N 96.45972°W / 35.35028; -96.45972 (35.350195, -96.459700). According to the United States Census Bureau, the town has a total area of 1.1 square miles (2.8 km²), all of it land.