Thacher, Thomas a Congregational minister, was born at Salisbury, England, May 1, 1620. He declined the offer of his father to send him to an English university, preferring to emigrate to America. On June 4, 1635, he arrived at Boston, Mass., and soon after entered the family of the Rev. Charles Chauncy, of Scituate. He was ordained pastor of the Weymouth Church, Jan. 2, 1644, where he labored for more than twenty years. He then removed to Boston, where he preached occasionally, but was principally engaged in the practice of medicine, till he was chosen first pastor of the Third (Old South) Church. His installation took place Feb. 16,1669, and after a happy ministry he died Oct.. 15, 1678. He wrote, A Brief Rule to Guide the Common People of New England how to Order Themselves and Theirs in the Small Pocks or Measles (Bost. 1677; 2d ed. 1702), said to be the first medical tract published in New England: — A Fast of God's Choosing, a sermon (1674, 4to; 1678). See Sprague, Annals of the Amer. Pulpit, 1, 126.