In 1994, the Library of Congress selected Marty (1955) for preservation in the National Film Registry, deeming the film "culturally, historically, or aesthetically significant" in the cultural legacy and movie history of the United States.
Betsy Blair, who portrayed Clara, was almost not permitted to do the film by Hecht-Lancaster Productions and United Artists due to the 1950s Hollywood Blacklist. However, Gene Kelly, her husband at the time, basically blackmailed United Artists and Hecht-Lancaster into casting her, at the last minute, by threatening not to direct or star in any of UA's or Hecht Lancaster's productions if she was not cast for the role.
Delbert Mann had no idea who to cast in the lead role, so asked his friend Robert Aldrich. Aldrich immediately suggested Ernest Borgnine. Mann was skeptical, as Borgnine was only known for playing heavies, but Aldrich convinced him. Borgnine regularly says that he owes his career to Robert Aldrich.
Paddy Chayefsky wrote the play (which originally appeared on television) as a starring vehicle for his friend, actor/director Martin Ritt, even naming the lead character after him. But Ritt had been blacklisted during the McCarthy "Red Scare" era and the network wouldn't allow him to be hired, and the role eventually went to Rod Steiger.
The most prominent uncredited role was Ralph, portrayed by Frank Sutton, who was later famous for his role of Sgt. Vince Carter on Gomer Pyle: USMC (1964), a military themed comedy, which was a ratings competitor, from 1964 to 1966, to the military themed comedy which Ernest Borgnine stared on, McHale's Navy (1962).
Rod Steiger, who had originated the role of Marty in the eponymous TV production, said that he turned down the role in the movie because the Hecht-Lancaster Productions contract would have bound him for years. Harold Hecht and Burt Lancaster, on the other hand, said that they did not want to cast Steiger as they felt the public would not go for the same actor that they had seen for free on TV.
The street scene behind the opening credits is Arthur Avenue at 187th Street in The Bronx, in front of the City of New York's old Arthur Avenue Retail Market under a billboard sign for Knickerbocker Beer, an actual New York City brand, brewed by the Ruppert Brewing Company, the family business of Colonel Jacob Ruppert, owner of the New York Yankees from 1915 to 1939, also known as the Bronx Bombers, which is where the film is set.
Washington lawyer Edward Bennett Williams was offered a 10% ownership in the movie in lieu of a fee for legal work he had done. He turned down the stake and took his fee, thus losing a considerable amount of money.
The character of Leo, who appears in the back of the car when Marty is approached by his friends to make up the pair for the "odd squirrel" they have with them. According to Delbert Mann, Chayefsky (who was once a moderately renowned stage actor) was recruited for the very visually obscured part solely to save the time and money of hiring an extra. According to Chayefsky, for his three lines he was required to rejoin the actor's union, which required dues of $140. He recalled the role as paying about $67.