Along the way, she collected a record 12 Oscar nominations and four Best Actress Oscars.
Meryl Streep broke Hepburn's nomination record last year with her 13th nomination, for "Adaptation." Jack Nicholson earned his 12th nomination last year for "About Schmidt." Three actors -- Nicholson, Ingrid Bergman and Walter Brennan -- are three-time Oscars-winners.
To put Hepburn's Oscar record in perspective, note that the lengthy list of Hollywood legends who never managed even one Academy Award includes Richard Burton, Marlene Dietrich, Errol Flynn, Greta Garbo, Judy Garland, Bob Hope and Robert Mitchum.
Hepburn's first Oscar nomination -- and first win -- came in her second year in Hollywood, for her performance in "Morning Glory" as Eva Lovelace, an aspiring New York actress who attracts the interest of a playboy producer, an older actor and an overly earnest young playwright.
In the same year, Hepburn starred as Jo March in "Little Women," which was nominated for Best Picture. It was one of her many successful collaborations with George Cukor, who also directed Hepburn in "The Philadelphia Story" (1940) and "Pat and Mike" (1952) -- one of nine movies Hepburn made with Spencer Tracy, beginning in 1942 when they co-starred in "Woman of the Year" and "Keeper of the Flame."
The collaboration, like the then-secret and long-running love affair between the screen legends, lasted until Tracy's death in 1966, just days after he finished filming "Guess Who's Coming to Dinner?" Hepburn won her second Oscar and Tracy received his ninth nomination for their performances as liberal white parents who have difficulty dealing with their daughter's spur-of-the-moment decision to marry a black man, played by Sidney Poitier.
Hepburn did not attend the Academy Awards ceremony that year, a gesture of deference to Tracy's widow, Louise. Tracy was Catholic, so he and his wife never divorced, although they lived apart and Tracy shared a very private home with Hepburn.
Hepburn collected her third Best Actress Oscar the following year for her portrayal of Queen Eleanor of Aquitaine in "The Lion in Winter," finishing in a tie with Barbra Streisand for "Funny Girl."
Her next nomination came in 1981, when she and Henry Fonda won for Best Actress and Actor -- playing Ethel and Norman Thayer in the Best Picture nominee, "On Golden Pond."
Fonda -- who died a few months after the Academy Awards ceremonies -- picked up the first Oscar of his distinguished film career. Hepburn, at 73, collected an unprecedented fourth acting Oscar.
"I was so dumbfounded," she told reporters on Oscar night. "I'm so touched that my fellow actors cared to vote for me, a dear old thing."
Screenwriter Fay Kanin, whose husband Michael Kanin wrote "Woman of the Year," said Hepburn was down to earth offscreen -- as feisty as the characters she played.
"She called me once and said, 'Fay, I have a favor to ask of you,'" recalled Kanin. "There is a group out there in Los Angeles, something to do with parent-teachers. They want to give me an award and you know I'm not going to come out there and get an award but I'm not going to turn them down. Would you do it?'"
Kanin said she would.
"I said you'd do the same for me," said Kanin. "Katharine said, 'No I wouldn't.' She was nothing if not frank."
Mark Rydell, the Oscar-nominated director of "On Golden Pond," said Hepburn was "a ferocious and remarkable human being." Rydell said working with Hepburn was "one of the great experiences" of his life.
"I had a glorious summer with her," said Rydell. "I had the privilege of introducing Katharine Hepburn to Henry Fonda. She was feisty and at the same time a completely dedicated actress who was able to do anything I asked her."
Befitting her status as one of Hollywood's elite, Hepburn onscreen was constantly surrounded by screen legends and Oscar-winners. Hepburn's co-stars included James Stewart, Cary Grant, Humphrey Bogart, Elizabeth Taylor, John Wayne, Burt Lancaster and Warren Beatty.
The list of directors Hepburn worked with includes Hollywood giants such as John Ford, John Huston, Howard Hawks, Sidney Lumet and George Stevens. By far, her most fruitful collaboration was with the great Cukor, who won the Oscar for Best Director for "My Fair Lady" in 1964, and the D.W. Griffith Award -- one of the highest honors given by the Academy of Motion Picture Arts & Sciences -- in 1980.
They made nine features and two TV movies together. "Little Women" and "The Philadelphia Story" were nominated for best picture Oscars.
Hepburn won an Emmy for her performance in the 1975 Cukor-directed TV movie, "Love Among the Ruins," playing a wealthy older woman opposite another acting legend, Laurence Olivier. Hepburn collaborated with Cukor for one more TV movie, starring in the 1979 production of "The Corn Is Green."
After her 1981 performance in "On Golden Pond," Hepburn cut back considerably on her professional activity, appearing in a few movie documentaries and TV specials -- including the autobiographical "Katharine Hepburn: All About Me" in 1992.
In 1994, Hepburn appeared in "Love Affair," Warren Beatty's remake of "An Affair to Remember." The movie -- starring Beatty and his wife, Annette Bening -- was a critical and commercial disappointment, but film historian Leonard Maltin said Hepburn's performance as Beatty's "feisty aunt" was the high point of the picture.
Hepburn's obituary writers are giving that word -- "feisty" -- a thorough workout, probably owing to her tenacity in establishing a Hollywood career, overcoming early harsh reviews and becoming the most decorated Hollywood star of the 20th century.