Katharine Houghton Hepburn (May 12, 1907 – June 29, 2003) was an American actress in film, stage, and television. Her career as a Hollywood leading lady spanned over 60 years. She was known for her headstrong independence, spirited personality, and outspokenness, cultivating a screen persona that matched this public image, and regularly playing strong-willed, sophisticated women. Her work was in a range of genres, from screwball comedy to literary drama, and earned her various accolades, including four Academy Awards for Best Actress—a record for any performer. In 1999, Hepburn was named the greatest female star of classic Hollywood cinema by the American Film Institute.

Raised in Connecticut by wealthy, progressive parents, Hepburn began to act while at Bryn Mawr College. Favorable reviews of her work on Broadway brought her to the attention of Hollywood. Her early years in film brought her international fame, including an Academy Award for Best Actress for her third film, Morning Glory (1933), but this was followed by a series of commercial failures culminating in the critically lauded box office failure Bringing Up Baby (1938). Hepburn masterminded her own comeback, buying out her contract with RKO Radio Pictures and acquiring the film rights to The Philadelphia Story, which she sold on the condition that she be the star. That comedy film was a box office success and landed her a third Academy Award nomination. In the 1940s, she was contracted to Metro-Goldwyn-Mayer, where her career focused on an alliance with Spencer Tracy. The screen partnership spanned 26 years and produced nine films.

Hepburn challenged herself in the latter half of her life as she tackled Shakespearean stage productions and a range of literary roles. She found a niche playing mature, independent, and sometimes unmarried women such as in The African Queen (1951), a persona the public embraced. Hepburn received three more Academy Awards for her performances in Guess Who's Coming to Dinner (1967), The Lion in Winter (1968), and On Golden Pond (1981). In the 1970s, she began appearing in television films, which later became her focus. She made her final screen appearance at the age of 87. After a period of inactivity and ill health, Hepburn died in 2003 at the age of 96.

Hepburn shunned the Hollywood publicity machine and refused to conform to society's expectations of women, famously wearing trousers before they were fashionable for women. She was briefly married as a young woman but thereafter lived independently. With her unconventional lifestyle and the independent characters she brought to the screen, Hepburn epitomized the "modern woman" in the 20th-century United States and is remembered as an important cultural figure.