He has two daughters, Susan and Juliet, from his marriage to Space: 1999 co-star Barbara Bain.

Landau has appeared in countless films and shows since the late 1950s. Among his many credits:

• Hollywood Homicide (2003)
• The Majestic (2001)
• Sleepy Hollow (1999)
• Bonanno: A Godfather's Story (1999)
• The Joyriders (1999)
• The X-Files: Fight the Future (1998)
• Ed Wood (1994) (Academy Award winner, Best Supporting Actor)
• Intersection (1994)
• Eye of the Stranger (1993)
• Sliver (1993)
• The Fall of the House of Usher (1982)
• The Harlem Globetrotters on Gilligan's Island (1981)
• Space: 1999 (1975) TV Series
• They Call Me MISTER Tibbs (1970)
• Mission: Impossible (1966-69) TV Series
• The Greatest Story Ever Told (1965)
• Cleopatra (1963)
• North by Northwest (1959)
• Pork Chop Hill (1959)