Samuel Atkinson "Sam" Waterston (born November 15, 1940) is an American actor, producer, and director. He is best known for playing Executive Assistant District Attorney Jack McCoy in "Law & Order", and also for playing Sydney Schanberg in the 1984 movie "The Killing Fields". He won a Screen Actors Guild Award for his work on "Law & Order". He has also been nominated for an Emmy Award and a Golden Globe Award for that show. He has won other awards, too. He has also been nominated for a lot of awards.