William Holt Averell was the son of James Averell and Marcy Holt Averell. He was born in Cooperstown, New York in 1794. As a young man, he assisted with his father's store and tannery business. He was prepared for more advanced studies at the Fairfield Academy in Connecticut. Averell eventually received his A.B. from Union College in 1816 and then attended the Litchfield Law School in 1817. His sister Marcia attended the Litchfield Female Academy from 1811 to 1813. He married Jane Russell in 1829 at Claverack, New York. She died only four years later in Cooperstown in 1833. Averell was more actively involved with business and banking than with legal practice during his lifetime. He was the director of the Otsego County Bank, which later became First National, from 1830 until his death in 1873. He was also involved in land speculation and cotton manufacturing.