|Father Barry, played by Karl Malden|
The role played by Karl Malden was that of Father Barry, who was based on a real priest - Father John Corridon. According to Wikipedia:
Son of a County Kerry-born policeman in New York's Harlem, Corridan graduated from Manhattan's Regis High School in 1928. Father Corridan was assigned to the Xavier Institute of Industrial Relations on Manhattan's West Side in 1946. He became a passionate advocate of reform in the International Longshoremen's Association waterfront union.
Father Corridan collaborated with Malcolm in Johnson's articles on waterfront corruption. He was the subject of a 1955 biography, Waterfront Priest by Allen Raymond. The introduction of the book was by Budd Schulberg, screenwriter of On the Waterfront, who described how he met with Father Corridan frequently in researching the screenplay.
Schulberg described Father Corridan as a "tall, youthful, balding, energetic, ruddy-faced Irishman whose speech was a fascinating blend of Hell's Kitchen jargon, baseball slang, the facts and figures of a master in economics and the undeniable humanity of Christ."
Schulberg wrote that Father Corridan "led me to understand that there is nothing unusual about a Catholic priest's involving himself in moral issues that find practical form in the daily lives of his parishioners."
According to a 1983 article in the New York Times, Father Corridan's work was instrumental in formation of the New York-New Jersey Waterfront Commission aimed at curbing waterfront crime. Father Corridan, then retired, told a Times reporter that he believed that conditions on the waterfront had changed over the years.
The exterior shots of Father Barry's church in the movie is Our Lady of Grace in Hoboken, NJ (where the movie was filmed).
Interior shots of the church were filmed at St. Peter and Paul in Hoboken.