Ruby Dee, one of the most enduring actresses of theater and film, whose public profile and activist passions made her, along with her husband, Ossie Davis, a leading advocate for civil rights both in show business and in the wider world. Ms. Dee herself went from being a disciple of Paul Robeson to a co-star of Mr. Poitier, a featured player in the films of Spike Lee and an Oscar nominee for a supporting role; in the 2007 film “American Gangster,” about a Harlem drug lord (Denzel Washington), she was the loving mother, who turned a blind eye to her son’s criminality. She entered Hunter College in 1940. By the mid-1940s, when she graduated from Hunter, she was already a working actress, having appeared on Broadway and in productions of the American Negro Theater, then a fledgling professional company housed in the basement of the Harlem branch of the New York Public Library. She had also been married, in 1941, to the singer Frankie Dee Brown. The marriage dissolved within four years, but it gave Ms. Dee the name by which she would be known for the rest of her life. She made her Broadway debut in December 1943 in a short-lived play called “South Pacific,” unrelated to the Rodgers and Hammerstein musical that came along more than five years later. In 1946 she joined the cast of a Broadway-bound play called “Jeb,” about a black soldier who has lost a leg in World War II and discovers that his sacrifice for his country is of little value in the face of the racism he encounters on his return home. Hired as the understudy for the role of Libby, the title character’s loving girlfriend, Ms. Dee not only replaced the original actress in the role before opening night; she also fell in love with the star, Ossie Davis. The show lasted nine performances, the relationship nearly 60 years, until Mr. Davis’s death in 2005. They married in 1948. Besides her daughter Nora, Ms. Dee is survived by another daughter, Hasna Muhammad; a son, Guy Davis; a sister, Angelina Roach; and seven grandchildren.