Michael Costley, soldier and Texas Ranger, was born in 1809. Though he may have moved to Texas as early as 1827, his arrival was more likely in the spring of 1832. He settled first in the San Augustine area and then in Nacogdoches. He served in the Texas army from June 22 to September 22, 1836, and, under Hugh McLeod, patrolled the Bexar Road between the Angelina and Neches rivers in the summer of 1836. Costley recruited a company of mounted rangers called the First Company of Texas Rangers and served as its captain from September 11 to December 11, 1836, when Sam Houston discharged him and his company for refusing to obey orders. In 1836 or 1837 he founded the town of Douglass in Nacogdoches County. Costley had married Mahalah Mussett, daughter of William Mussett, by bond (i.e., by written agreement in the absence of a priest) on January 18, 1827, probably in Missouri, and they had a son. He eventually abandoned his first wife and had two sons with Elizabeth Reed, daughter of Jacob Reed. They later married on September 19, 1837, in Nacogdoches County. Costley never obtained a divorce from his first wife. His bigamy set the stage for years of litigation among his heirs. Costley died of a pistol wound inflicted by W. R. D. Speight, the first district clerk of Nacogdoches County, on November 16, 1837. At the time of Costley's death, he and Joseph S. Able were operating a store, Costley and Able, in Douglass.