John Uhler Lemmon III (February 8, 1925 – June 27, 2001) was an American actor. Considered equally proficient in both dramatic and comic roles, Lemmon was known for his anxious, middle-class everyman screen persona in dramedy pictures, leading The Guardian to coin him "the most successful tragi-comedian of his age."

He starred in over sixty films and was nominated for an Academy Award eight times, winning twice, and received many other accolades, including six Golden Globe Awards (counting the honorary Cecil B. DeMille Award), two Cannes Film Festival Awards, two Volpi Cups, one Silver Bear, three BAFTA Awards, and two Emmy Awards. In 1988, he was awarded the American Film Institute's Lifetime Achievement Award for his contributions to the American cinema.

His best known films include Mister Roberts (1955, for which he won the year's Oscar for Best Supporting Actor), Some Like It Hot (1959), The Apartment (1960), Days of Wine and Roses (1962), Irma la Douce (1963), The Great Race (1965), Save the Tiger (1973, for which he won Best Actor), The China Syndrome (1979), Missing (1982), and Glengarry Glen Ross (1992). He also acted in several Broadway plays, earning Tony Award nominations for Tribute and the 1986 revival of Long Day's Journey into Night.

Lemmon had a long-running collaboration with actor and real-life friend Walter Matthau, which The New York Times called "one of Hollywood's most successful pairings," that spanned ten films between 1966 and 1998; The Fortune Cookie (1966), The Odd Couple (1968) and its sequel The Odd Couple II (1998), The Front Page (1974), Buddy Buddy (1981), JFK (1991), Grumpy Old Men (1993) and its sequel Grumpier Old Men (1995), The Grass Harp (1995), and Out to Sea (1997).