The actor and civil rights activist Ruby Dee, who has died aged 91, played an important part in the struggle for equality for African Americans, both inside and outside show business.
She first made an impression in A Raisin in the Sun (1959), Lorraine Hansberry's groundbreaking Broadway drama, which coincided with the rise of the American civil rights movement. In the play, about a down-at-heel black family seeking a better life in a segregated section of Chicago, Dee played Ruth Younger, Sidney Poitier's level-headed, long-suffering wife. She repeated the role in the film version two years later, for which she won the National Board of Review award for best supporting actress.
It had taken her over 20 years in theatre and films to gain such recognition. From the early 1940s, Dee had appeared in productions of the American Negro Theatre (ANT), other members of which were Poitier, Harry Belafonte and Ossie Davis, whom Dee was to marry in 1948. It was an ANT production of Philip Yordan's all-black play Anna Lucasta, in which she starred on Broadway (taking over from Hilda Simms) in 1944.
She was born Ruby Ann Wallace in Cleveland, Ohio. (She took the name Dee from her first husband, the singer Frankie Dee Brown, to whom she was married from 1941 to 1945.) After her mother left the family, she was brought up in Harlem by her father, Marshall, a waiter on the Pennsylvania railroad, and graduated in 1945 from Hunter College, New York.
She first appeared in several low-budget films with all-black casts, specifically created for African-American audiences to be shown in segregated cinemas. In contrast to Hollywood productions, their black heroes and heroines were depicted as vital, ambitious and assertive.
When Dee began to appear in mainstream movies, she had to be content with more passive roles, to which she brought sympathy and warmth. In The Jackie Robinson Story (1950), a well-meaning biopic about the first black man to play in major-league baseball, she played Jackie's supportive wife. There were similar roles in Go Man Go (1954) and Edge of the City (1957), in both of which she was paired with Poitier. In another biopic, St Louis Blues (1958), she played the patient fiancee of the musician WC Handy (Nat King Cole), but she was finally allowed some eroticism in Take a Giant Step (1959), in which, as a widowed housemaid, she is the confidante of a mixed-up 17-year-old (Johnny Nash).
During the 60s, Dee was active in television, taking the role of Alma Miles in 20 episodes of Peyton Place (1968-69). On Broadway, she co-starred with her husband in his comedy Purlie Victorious (1961-62), roles which they repeated in the screen version, the renamed Gone Are the Days! (1963). She played Kate in The Taming of the Shrew and Cordelia in King Lear, the first black woman to appear in major roles at the 1965 American Shakespeare festival in Connecticut.
Dee's involvement in the civil rights movement began to be expressed in her work, as in her role in Jules Dassin's Uptight (1968) as the tender girlfriend of a moderate turned militant (Raymond St Jacques). In 1970, Dee triumphed opposite James Earl Jones in Athol Fugard's anti-apartheid play Boesman and Lena, at the Circle-in-the-Square, off Broadway, for which she won an Obie and a Drama Desk award.
It was inevitable that Dee would be cast in two of Spike Lee's best movies, Do the Right Thing (1989) and Jungle Fever (1991), because they examined a hitherto unexplored range of themes from a black perspective. In the former, Dee plays Mother Sister, a sort of neighbourhood witch, and in the latter, the sensible and forgiving mother of a married black architect (Wesley Snipes) who is involved with a white girl.
Dee continued to appear in films, on stage and on television, but much of her and her husband's time was taken up with activities organised by the Congress of Racial Equality, the Student Non-Violent Coordinating Committee, the Southern Christian Leadership Conference and the National Association for the Advancement of Coloured People.They were friends and supporters of both Martin Luther King and Malcolm X, raised money for the Black Panthers and demonstrated against the Vietnam war. In some ways, they made an odd couple: she was petite and stylish, he was large and bluff. "We shared a great deal in common; we didn't have any distractions as to where we stood in society. We were black activists. We had a common understanding," Dee told Ebony magazine in 1988.
In 2007, Dee received a best supporting actress Oscar nomination for her role as the feisty mother of a Harlem drug lord (Denzel Washington) in Ridley Scott's American Gangster.
She is survived by Guy, Nora and Hasna, her three children with Davis. He died in 2005.
• Ruby Dee, actor, born 27 October 1924; died 11 June 2014
guardian.co.uk © Guardian News and Media Limited 2010