Walter Slezak (German pronunciation: [ˌvaltɐ ˈslɛzak]; 3 May 1902 – 21 April 1983) was an Austrian-born film and stage actor active between 1922 and 1976.

Slezak typically portrayed wily and loquacious characters, often philosophical, and often with a taste for food, drink, and fine living.

He played a crafty villain as a U-boat captain in Alfred Hitchcock's film Lifeboat (1944), a charming, two-timing major domo to a tycoon in Come September (1961), and a wandering gypsy in The Inspector General (1949).

[1] He worked steadily and appeared in over 100 films including The Princess and the Pirate (1944), The Spanish Main (1945), Sinbad the Sailor (1947), Born to Kill (1947), Abbott and Costello in the Foreign Legion (1950), People Will Talk (1951), and Call Me Madam (1953).

In the 1970s, Slezak played the non-singing role of Frosch, the jailer, in the San Francisco Opera production of Johann Strauss's operetta Die Fledermaus.

[1] He was reportedly despondent over the state of his health, most notably heart trouble, a recent prostate operation, and a shoulder injury requiring several treatments a week.

During a performance in the title role of Lohengrin, the elder Slezak was supposed to finish his aria by stepping into a swan boat and then being pulled offstage.