Irving John ("I. J."; "Jack") Good (9 December 1916 – 5 April 2009)was a British mathematician who worked as a cryptologist at Bletchley Park with Alan Turing. After the Second World War, Good continued to work with Turing on the design of computers and Bayesian statistics at the University of Manchester. Good moved to the United States where he was professor at Virginia Tech. He was born Isadore Jacob Gudak to a Polish Jewish family in London. He later anglicised his name to Irving John Good and signed his publications "I. J. Good."