William was born in England. He was the son of Reverand William Thompson of Braintree. William married Katherine Treat, daughter of Richard Treat and Alice Gaylord, on 19 November 1655 in New Haven, New Haven County, Connecticut.1
|Katherine Treat b. b 29 Jun 1637|
- [S115] Genealogical Dictionary of the First Settlers of New England, Showing Three Generations Of Those Who Came Before May, 1692, On The Basis Of Farmer's Registar, Volume IV: page 326.