When William King Seeley was born on 12 November 1787, in Stamford, Fairfield, Connecticut, United States, his father, Silvanus Seeley Jr, was 23 and his mother, Mary Hoyt, was 23. He married Deborah Raymond on 17 February 1809, in New Canaan, Fairfield, Connecticut, United States. They were the parents of at least 3 sons and 5 daughters. He lived in Masonville, Delaware, New York, United States in 1850 and Walton, Delaware, New York, United States in 1860. He died on 11 November 1864, in Walton, Walton, Delaware, New York, United States, at the age of 76, and was buried in Northfield, Walton, Delaware, New York, United States.