Theodore Dwight Weld Facts. Theodore Dwight Weld (1803-1895) was an American reformer, preacher, and editor. He was one of the most-influential leaders in the early phases of the antislavery movement. Theodore Weld was born in Hampton, Conn., on Nov. 23, 1803, the son of a Congregational minister. Sent to Phillips-Andover to prepare for the ministry, he was forced to leave because of failing eyesight; he tried lecturing and later entered Hamilton College in New York.