Nearly 40 years on, Rocky remains Sylvester Stallone's best film, a loud counter-argument to those who claim he can't act.
While its classic status in inarguable, how much do you know about the equal greatest* boxing movie ever made?
*Tied with Raging Bull, obviously
Rocky was the first sports movie to ever win an Academy Award for Best Picture.
Rocky's dog Butkus was Sylvester Stallone's dog in real life.
In the meat locker scene, Stallone spent so long punching the animal carcasses that he permanently flattened out his knuckles.
Stallone wrote the first draft of the script in just three days. Slightly spoiling this story, there were actually several rewrites to get to the version that was shot.
When United Artists offered to buy Stallone's script they were not interested in him playing the lead, preferring to cast an established star like Ryan O'Neal, Robert Redford, James Caan or Burt Reynolds. Stallone insisted that he wouldn't sell the script unless he played the title role. UA relented but cut the proposed $2 million in half.
Earlier drafts of the script had Mickey as an angry racist and Rocky throwing the final fight because he no longer wanted to be part of the professional boxing world.
Rocky's production budget was $1,075,000. It would go on to earn over $225 million worldwide.
Burgess Meredith got the role of Mickey because all the other actors that Stallone approached were insulted that he wanted them to audition rather than just take the role.
Susan Sarandon auditioned for the role of Adrian but was considered too pretty. Cher was also considered for the role.
Carl Weathers says that the budget on the film was so low that he and Burgess Meredith had to share a tiny dressing room.
Stallone was inspired to write the movie after seeing unfancied boxer Chuck Wepner last fifteen rounds with Muhammad Ali at the Richfield Coliseum on March 24, 1975.
The two scenes in which Rocky runs up the stairs of the stairs of the Philadelphia Museum - once when he can't do it and once when he, after much training, triumphantly can - were filmed two hours apart.
The budget didn't allow for a sufficiently large crowd to fill the arena in the final fight scene, so stock footage of sporting crowd scenes had to be used to fill out the editing. However, you can still see in some shots that some of the seats are empty.
Several members of Stallone's family were involved in the making of the film. His father plays the man who rings the bell to start a round, his brother plays a street singer and his first wife, Sasha, was the productions stills photographer.
Before directing the film, John G. Avildsen had never watched a boxing match or a boxing movie.
You can buy and re-live Rocky on Blu-ray by clicking here.