With Jack Lemmon in The Days of Wine And Roses, Blake Edwards, 1962. Sober cinephiles the world over will tell you that Klugman's character Jim is pretty much the platonic ideal of an AA sponsor. It is no insult to say that nobody did Jack Klugman better. An exemplary performer, and he sounded like a pretty exemplary man, too. Rest in peace.
UPDATE: Joseph Failla sends some observations: