American screen and stage actor adept at both comedy and drama and noted for his portrayals of high-strung or neurotic characters in American films from the 1950s onward.

Lemmon attended Harvard University and was president of the school's Hasty Pudding Club, an organization renowned for its annual satiric revues. Upon graduation in 1947, he served in the navy, after which he moved to New York City. There he worked as a piano player and actor, making his Broadway debut in a revival of the farce Room Service (1953). Although the production was unsuccessful, his performance led to a contract with Columbia Pictures (Columbia Pictures Entertainment, Inc.) the following year.

His first two film appearances were opposite Judy Holliday (Holliday, Judy) in It Should Happen to You and Phffft! (both 1954). His Oscar-winning performance as Ensign Pulver in Mister Roberts (1955) firmly established him as one of the screen's brightest new comic actors. He went on to deliver solid performances in other comedies, including My Sister Eileen (1955), Operation Mad Ball (1957), Bell, Book and Candle (1958), and It Happened to Jane (1959). Two films directed by Billy Wilder (Wilder, Billy) helped establish Lemmon as a major star. Some Like It Hot (1959), an American comedy classic, featured Lemmon as a jazz musician posing as a woman, and The Apartment (1960) reinforced the character type for which he became known, that of a tense, excitable, and baffled individual who painfully progresses to a deeper understanding of the world. He received Oscar nominations for both films, as well as for Days of Wine and Roses (1962), in which he gave a harrowing portrayal of an alcoholic advertising executive.

Wilder teamed Lemmon with Walter Matthau (Matthau, Walter) in The Fortune Cookie (1966), the first of many comedies for the pair. Their most famous teaming was in The Odd Couple (1968), based on Neil Simon (Simon, Neil)'s stage hit. The film established the pattern for most of their appearances together, with a fussy neurotic (Lemmon) butting heads with a carefree scalawag (Matthau). Other Lemmon-Matthau films include The Front Page (1974), Buddy Buddy (1981), Grumpy Old Men (1993), Grumpier Old Men (1995), and The Odd Couple II (1998).

In the 1970s Lemmon made his directorial debut with Kotch (1970), starring Matthau, and won his second Oscar for his performance in Save the Tiger (1973). He appeared in two more Neil Simon comedies, The Out-of-Towners (1970) and The Prisoner of Second Avenue (1974), and garnered additional Oscar nominations for The China Syndrome (1979), Tribute (1980), and Missing (1982).

As he aged into character roles, Lemmon remained no less prolific. His acclaimed performances of later years include his portrayal of James Tyrone in Eugene O'Neill's Long Day's Journey into Night in both a stage revival (1986) and a television adaptation (1987); a down-and-out real estate salesman in Glengarry Glen Ross (1992); a smooth-talking con man in The Grass Harp (1995); and two TV renderings of classic American dramas, 12 Angry Men (1997) and Inherit the Wind (1999), both of which costarred George C. Scott (Scott, George C.). Lemmon also won an Emmy Award for his touching portrayal of a dying college professor in the television film Tuesdays with Morrie (1999).