William Thomas Sadler (born April 13, 1950) is an American film and television actor. His television and motion picture roles have included Chesty Puller in The Pacific, Luther Sloan in Star Trek: Deep Space Nine, Sheriff Jim Valenti in Roswell, convict Heywood in The Shawshank Redemption, Senator Vernon Trent in Hard to Kill, and the Grim Reaper in Bill & Ted's Bogus Journey, a role for which he won the Saturn Award for Best Supporting Actor, and his role as Colonel Stuart opposite Bruce Willis in Die Hard 2. He played the character of President of the United States, Matthew Ellis, in Iron Man 3, in Marvel's Agents of S.H.I.E.L.D., and in WHIH Newsfront. He also recurs as Steve McGarrett's murdered father, John McGarrett, in the 2010 remake of the 1968 television series, Hawaii Five-O.
He is also known as William Thomas Sadler.