Blair, who was blacklisted in Hollywood in the 1950s while married to screen legend Gene Kelly and later was married to director Karel Reisz, died of cancer in a hospital in London on March 13, said her daughter, Kerry Kelly Novick.
The red-haired actress earned an Academy Award nomination as best actress in a supporting role as Clara Snyder in "Marty," which won the Academy Award for best picture -- as well as Oscars for screenwriter Paddy Chayefsky, director Delbert Mann and Borgnine.
Blair, Los Angeles Times movie critic Edwin Schallert wrote in his review, "shines right along with [Borgnine] as the gentle and understanding wallflower whom he meets in the dance hall, and with whom he finds deep and mutual understanding, because he seems to be such a bull in a china shop himself."
Of the on-screen pairing of Borgnine and Blair in the film, in which "lonely boy meets lonely girl," New York Times film critic Bosley Crowther wrote, "the two make an excellent team."
Borgnine told the Los Angeles Times this week that he had just been thinking about Blair while signing autographs to be inserted into copies of his recently published autobiography for a promotional trip to London in April when he learned of her death.
"I was thinking to myself, 'Gee, she was always on time, she was a wonderful woman, very quiet-spoken, and the nicest person you could ever want to meet,' " Borgnine said. "She carried herself well, and she knew her business. I thought she was deserving [of the Oscar], but other thoughts prevailed, I guess."
Jo Van Fleet won for "East of Eden."
Blair's performance in "Marty," Borgnine said, "was absolutely lovely. It was a pleasure working with her."
Blair, however, almost didn't get to play Clara, a role that Chayefsky had recommended her for: She had been blacklisted since 1950.
The actress, who had attended a weekly Marxist study group in New York City when she was 16, later came under the scrutiny of the FBI for her association with left-wing organizations such as the Joint Anti-Fascist Refugee Committee, the Sleepy Lagoon Committee and the Civil Rights Congress.
But Blair's ideals "had always been American, not Russian," she wrote in her 2003 memoir, “The Memory of All That.” And her "battles and contribution -- small as it may have been -- were against racism, for strong unions, for the rights of women; to put it simply, for democracy."
It wasn't until Blair had done three impressive readings for the role of Clara that the subject of the blacklist came up when producer Harold Hecht phoned her and apologetically asked her if she would write a letter that would "clear" her.
As Blair recounted in her memoir, Hecht told her that she didn't have to "name names" -- at least not names that hadn't already been exposed.
She wanted the part so badly that she agreed to write a letter without names. In her letter, which she described as sounding "like a schoolgirl essay for civics class," she expressed her love for her country and "went on about freedom of speech and the American Constitution and the secret ballot."
But, she wrote in her book, "both Harold Hecht and I knew it wouldn't pass muster. It didn't come near what the Un-American Activities Committee wanted -- no, demanded."
Finally, husband Kelly -- one of MGM's biggest stars -- intervened by asking studio head Dore Schary "to do something" to help his wife get the part or he'd stop shooting the movie he was working on.
"And Dore did," Blair wrote. "He called the American Legion in Washington right there and then in front of Gene, and he vouched for me. And so I was in 'Marty.' "
In 1957, the year after she received her Oscar nomination, Blair and Kelly were divorced, and Blair moved to Paris.