William Pendleton was born in Westerly, Rhode Island, March 23, 1704. He was the second of three sons of Joseph Pendleton and his second wife Patience Potts. William was baptized in the Congregational Church on May 28, 1704. He was one of the council which formed the Church of Christ in 1742. He became a Deacon in 1752. He was a justice of the peace, served as a representative in the General Assembly of Rhode Island, and was a Major in the Third Regiment of King's County militia. He became Colonel in 1750 and served as muster master in the French and Indian War. William was president of Westerly Town Council 1762 1781 (member of town council 1757-1781). He raised soldiers for the Revolutionary War.
William married Lydia Burrows of Groton, Connecticut, (b. 1703) on March 10, 1725. They had nine children: William, Amos, Freelove, Lydia, Peleg, John, Benjamin, Joshua and Ephraim, Lydia, William's wife, died in Westerly, Rhode Island, in August 1750. William Pendleton married his second wife, Mrs. Mary Chesehrough (widow) on April 4, 1751. There were four children by this marriage, two sons and two daughters: Nathan, Keturah, Lucy, and Isaac (who drowned at age twenty).
William Pendleton was a farmer in 1829, raising cattle and horses, and was a Freeman of Westerly, Rhode Island. He became inspector of commodities in 1734 to 1744 and was juryman 1734, 1743, and 1754. He was Deputy to the Rhode Island General Assemble in 1746. William Pendleton had an excellent reputation for fairness and square dealing. He served as head of Westerly Town Council from 1762 to 1781, a total of nineteen years. He died in Westerly, Rhode Island, on August 23, 1786 at age 82.