William King was born on February 9, 1768, in Scarboro, Maine, then still part of Massachusetts. His formal education was limited, ending at the age of 13. An enterprising nature compensated for his lack of schooling. Beginning work in a Topsham sawmill, he became the largest ship owner in Maine and a successful merchant. King also owned extensive real estate, was a principal owner of Maine's first cotton mill in Brunswick, and was a founder and president of Bath's first bank.
Active in local politics beginning in 1795, he served in Massachusetts General Court, representing Topsham in 1795 and 1799 and Bath in 1804. He served twice as state senator for Lincoln County, from 1807 to 1811 and 1818 to 1819. During the War of 1812 he served as major general in the militia and provided recruiting assistance as a colonel in the United States Army. As a major shipper, he directed much of his attention to protecting the coastal and marine trade. In 1813, King began the effort for which he is best remembered. Residents of Maine had suffered hardships during the war and petitioned Massachusetts for separation. King worked for seven years and statehood for Maine was granted in 1820.
Elected its first governor, King served until 1821, when he was appointed commissioner to work on the treaty with Spain, a post he held for three years. Even though King was a poorly educated man, he was a trustee of Waterville (now Colby) College, and trustee and overseer of Bowdoin College. King died on June 17, 1852.