Thomas M. Coleman, pioneer Texas cattleman, the son of Lucy Catherine (White) and Youngs Levi Coleman, was born on August 15, 1833, at Liberty, Texas. The family moved to Gonzales and then Jackson County before moving to Goliad County. In the early 1850s Youngs Coleman bought San Patricio County land on Chiltipin Creek and at La Quinta on Corpus Christi Bay. The younger Coleman was associated with his father during this period as a rancher and cattleman in Goliad and San Patricio counties, and as foreman of operations headquartered at Rincon. In 1858 he and others formed the Star Cattle Company, which drove cattle to Chicago. He left the drive in 1859 to marry Margaret Susan Atlee of Athens, Tennessee, but the couple spent their honeymoon in New York trying to sell barrels of beef when poor market prices forced the company to slaughter more than 1,300 cattle and ship them east. The Colemans eventually had two children.
In 1871 Coleman was among the incorporators of the Rockport, Fulton, Laredo and Pacific Railroad, which became the Texas and Pacific in 1874. Also in 1871 at Rockport, Coleman and his father formed the Coleman, Mathis, Fulton Cattle Company with Thomas Henry Mathis, George Ware Fulton, and J. M. Mathis. The firm shipped cattle and operated a Rockport packery that manufactured tallow and shipped rawhides to factories. The partners sold their own land to the cattle company, borrowing money to pay the bill, and bought land for the new partnership, thus consolidating a spread of some 265,000 acres in Aransas, Goliad, and San Patricio counties with ranges leased in Refugio and other counties. In 1879 the partnership dissolved because of personal conflicts. The Mathis partners dropped out, taking with them land and a promissory note. A new company with 165,000 acres was reorganized in 1879 as the Coleman-Fulton Pasture Company. Though Coleman was manager of the new company at its inception, Fulton replaced him as ranch-operations head with George W. Fulton, Jr. The elder Fulton borrowed money from David Sinton to help the company survive drought, and Coleman later sold most of his stock to Sinton and Charles P. Taft, both of Cincinnati, Ohio. Though he retained the Chiltipin Ranch, where he built a $150,000 mansion to rival that of Fulton at Rockport, Coleman never recovered from the financial burden of the project. At his death, the land was given to a relative in payment of a loan, and the mansion was torn down in 1930.
Coleman served under Capt. R. H. Belvin in a reserve company of the Twenty-ninth Brigade, Confederate States of America, and in San Patricio County as a deputy inspector of brands. He was appointed to the commissioners' court in 1889 and 1891 but resigned in 1892. He married Frances Humphreys in 1872, after the death of his first wife. He was elected county judge in 1894 and suffered a heart attack as he was about to open court at Sinton. According to commissioners' court records he died on February 11, 1896. Coleman's son Thomas Atlee Coleman, a prominent San Antonio businessman and rancher, purchased the Milmo Ranch in Mexico, a spread of over a million acres, for which he paid $3.5 million dollars.