Samuel Taliaferro Rayburn (January 6, 1882 - November 16, 1961), widely known as Mr. Sam, was a Democratic politician from Bonham, Texas. He served as leader of the Democratic caucus in the U.S. House of Representatives from 1940 to 1961, being Speaker whenever the Democrats were in the majority, and at the time of his death was the longest-serving Congressman in US House history.