Frank C. Stilwell (1856 – March 20, 1882) was an outlaw Cowboy who killed at least two men in Cochise County during 1877–82. Both killings were considered to have been self-defense. For four months he was a deputy sheriff in Tombstone, Arizona Territory for Cochise County Sheriff Johnny Behan. Stilwell owned interests in several mines and various businesses, including a saloon, a wholesale liquor business, a stage line, and at his death livery stables in Charleston and Bisbee. He was also a partner in a Bisbee-area saloon with ex-Texas Ranger Pete Spence.