Thomas C. Cater was born in South Carolina in 1834 to Silas McPherson Cater (1789–?) and Eliza Maria (Porcher) Cater (1793–?). From South Carolina, his family moved to Talladega, Alabama, where his father worked as a farmer. By 1860 Thomas Cater was living in Travis County, Texas, and had married Margaret McCall (1844-?) of Louisiana on January 3, 1860. The couple had five children: Elizabeth (1861–1934), Maggie (1864–?), Lula (1866–1957), Emma (1868–?), and Thomas (1870–1948).
At the outbreak of the Civil War, Thomas Cater became the first commander of Cater's Texas Cavalry battalion with the rank of major. The battalion was organized in mid-1864 and disbanded after August 1864. Their assignment was Western Sub-district, District of Texas, New Mexico and Arizona, Trans-Mississippi Department. Cater's Battalion took part in one skirmish at Palmito Ranch near Brownsville, Texas, on September 6, 1864. Officially, Cater's battalion surrendered at Galveston in June 1865, but it is doubtful that the unit was still in existence at that time. Most likely, the unit decided not to surrender formally, and there is at least one unofficial source that indicates that a detachment of Cater's Texas Calvary battalion crossed the Rio Grande into Mexico in mid-May 1865 rather than capitulate. Thomas Cater, however, surrendered with the forces of Gen. Edmund Kirby Smith at Galveston. He received parole and was released in Austin on July 27, 1865.
After the war, Thomas E. Cater had a retail grocery shop in the Swenson building on Congress at Bois d'Arc and Hickory Street in Austin, Texas. His grocery store was also listed as a liquor store. By 1872 his residence was listed, along with a Mrs. McCall, at Congress Avenue and Walnut Street in the same city. Thomas Cater continued to live and work in Austin, Texas, until his death on December 13, 1903.