Served in the US Army Air Force, 8th Air Force, 453rd Bombardment Group in England with James Stewart.
Step-father of Lucy Saroyan.
Studied in the dramatic workshop at New York's New School with Gene Saks, Rod Steiger, Harry Guardino and Tony Curtis.
Uncle of Juliette Gruber.
Very tall as young man (6' 3"), Matthau had a very slouchy posture by the time he was an actor. This was in part due to back injuries attained in combat in World War II, but he probably exaggerated it because the slouch fitted his miserly characters.
Was passionate about classical music and often sang pieces by Mozart on the set.
When he inscribed himself formally to the U.S. Social Security in 1937, he included "Foghorn" as his middle name. He never changed it.
While making a TV series in Florida before his movie stardom, he lost $183,000 betting on spring-training baseball games.
Won two Tony Awards: in 1962, as Best Supporting or Featured Actor (Dramatic) for "A Shot in the Dark," and in 1965 as Best Actor (Dramatic) for "The Odd Couple," recreating his part as Oscar Madison in the film version of the same name, The Odd Couple (1968). Previously, he also had a Tony nomination in 1959 as Best Supporting or Featured Actor (Dramatic) for "Once More, with Feeling."