John Cazale was born on August 12, 1935 in Boston, Massachusetts. During his youth he met Al Pacino and the two became close friends.

After graduating from high school, he studied drama and the theatrical arts at Oberlin College and Boston University. Throughout the 1960s, he starred in numerous stage productions and worked to establish himself as a versatile character actor. In 1967, he starred in the play "The Indian Wants the Bronx", written by Israel Horovitz. For his performance he was nominated for and won an Obie Award.

His debut on the silver screen came in the screen adaptation of Mario Puzo's "The Godfather". Cazale played the role of Fredo Corleone alongside his friend Al Pacino, who played Michael Corleone. The film was released in 1972 to much critical acclaim and rocketed Cazale into instant stardom.

In 1974, he reprised his role as Fredo in "The Godfather II". This film generated a great deal of critical acclaim and further established him as a big name in Hollywood. That year he also starred in "The Conversation" with Gene Hackman and Harrison Ford.

In 1975, he reunited on screen with Al Pacino in the film "Dog Day Afternoon". Cazale took on the role of Sal, a member of a group of bank robbers. In the film, what was supposed to be a quick in and out operation ended up turning in to a total disaster for the robbers. The film was a huge success and scored big at the box office.

Around this time, Cazale learned that he was afflicted with cancer in his bones. He decided to continue working and was nearly prevented from doing so when studios refused to insure him. Fortunately, his friends intervened and allowed him to get in one last film.

In 1978, he played the role of Stanley in the film "The Deer Hunter". Stanley lives in a small town with a close knit group of friends that work together at a factory. A number of the friends are sent to Vietnam and their lives are irreversibly changed for the worse. Although Cazale's role in the film was a supporting role, it was very well acted and had a great deal of emotional impact.

Cazale also became engaged to costar Meryl Streep while filming the film. Unfortunately, their relationship would prove to be short-lived due to his illness. His condition worsened throughout filming, forcing the studio to film his scenes first.

On March 12, 1978, he died from cancer. Today he remains the only actor to have all of their films listed in the top 250 at the IMDB. His death at the height of his career was a tragic occurrence and Pacino later stated that he had considered Cazale his acting partner and would have been willing to work with him the rest of his life.