Jack Lemmon (1925âÂÂ2001) and Walter Matthau (1920âÂÂ2000) were a pair of American male actors who starred in ten films together, co-starring in eight of them. In addition, Lemmon directed Kotch (1971), which starred Matthau (and had an uncredited cameo by Lemmon). Off-screen, they were best friends, though their characters constantly clashed on-screen.