Cause of death: heart attack
Martin James Landau (; June 20, 1928 – July 15, 2017) was an American actor. His career began in the 1950s, with early film appearances including a supporting role in Alfred Hitchcock's North by Northwest (1959). His career breakthrough came with leading roles in the television series Mission: Impossible (1966–1969) and Space: 1999 (1975–1977).
Landau earned Academy Award nominations for his performances in Tucker: The Man and His Dream (1988) and Woody Allen's Crimes and Misdemeanors (1989). He won the Academy Award for Best Supporting Actor as well as the Screen Actors Guild Award and a Golden Globe Award for his portrayal of Bela Lugosi in Ed Wood (1994). Other notable roles include in Cleopatra (1963), The Greatest Story Ever Told (1965), Rounders (1998), Sleepy Hollow (1999), and Remember (2015). He headed the Hollywood branch of the Actors Studio until his death in July 2017.
Source : Wikipedia