William Tennant Austin, soldier and civil servant of the Republic of Texas, was born on January 30, 1809, in Bridgeport, Connecticut, the son of Susan (Rogers) and John Punderson Austin. He began working at the age of eleven and by seventeen was established as a merchant. In 1826 he married Joana Thomas. He was the brother of John Austinqv of Brazoria. In October 1830, at the age of twenty-two, he arrived at that town on the schooner Nelson with his wife and daughter. His wife was, according to Archibald Austin, "a very pretty little woman" and "a very agreeable acquisition to the Society of Texas." On December 12 Stephen F. Austin had located land on Buffalo Bayou for William, who had established a mercantile trade before the end of the month. In 1832 William was wounded in the battle of Velasco, and in 1833 his wife, child, and brother all died in a cholera epidemic. Later that year the Brazos River flooded and washed away his store.

At Harrisburg on June 4, 1835, William Austin, along with William B. Travis, signed a document protesting the Mexican enforcement of customs duties and other restrictions at Anahuac and pledged himself to overthrow Mexican authority there. As an early member of the so-called war party, he joined William H. Whartonqv and several other citizens of the Columbia District on July 25, 1835, in calling for a general convention of all Texans. On August 15 he was appointed secretary of a meeting at Columbia, at the mouth of the Brazos, which established a committee of safety for the district and on August 20 called for a General Consultation. When Mexican general Martín Perfecto de Cosqv and 400 soldiers landed at Copano to suppress resistance to Antonio López de Santa Anna's Centralist government, Austin and Branch T. Archer called for volunteers to resist him with force. On October 2, 1835, Austin and nine other volunteers, including James W. Fannin, Jr., George Sutherland, and Archer, left Columbia to reinforce the Texan insurrectionists at Gonzales, thus becoming part of the nucleus of the army with which Gen. Stephen F. Austin and Col. Edward Burleson besieged Bexar that fall and winter. On October 12 General Austin commissioned William Austin a colonel and appointed him as one of his two aides-de-camp, the other being Peter W. Grayson. When Stephen Austin left the army to become the spokesman for the Texan cause in Washington, D.C., William Austin continued his duties as aide to the new commander, Edward Burleson. In their official reports on the storming of Bexar, both Burleson and adjutant general Francis W. Johnson commended Austin; Burleson observed to Governor Henry Smith that Austin's "conduct on this and every other occasion, merits my warmest praise." On March 14, 1836, Sam Houston appointed Austin his aide-de-camp with the rank of major and ordered him to Columbia to requisition artillery and horses for the army.

After the war Austin, who had married Elizabeth Bertrand on January 25, 1836, returned to his Brazoria County plantation. There in 1837 he was elected clerk of the Brazoria county court and, on January 21, 1838, was appointed collector of revenue for the port of Velasco. In 1840 he was a resident of Brazoria County, but by 1848 he had moved to Washington-on-the-Brazos, where he was once again a merchant. In 1854 he was in Galveston as a commission merchant and cotton factor. During the Civil War Austin served as Confederate marshal for East Texas and was appointed a brigadier general of state troops. He was a Democrat, a Mason, and an Episcopalian. He died at Galveston on February 25, 1874.