Sylvester Stallone says he rewrote 'Rocky' after a friend told him the character was too 'cruel'

• Netflix's documentary, "Sly," looks at the life and career of Sylvester Stallone.
• He recalled making the 1976 film "Rocky," and changes he made to the script.

Sylvester Stallone skyrocketed to fame after "Rocky" wowed audiences in 1976 with the story of a boxer who trains for a title bout against reigning heavyweight champion Apollo Creed (Carl Weathers). It raked in $117 million at the box office and led to several sequels, as well as the "Creed" spin-off movies.

But it almost had a much harder edge. In the new Netflix documentary "Sly," the actor and writer discussed how he initially conceived of the project.

He explained that he was inspired by Martin Scorsese's crime drama "Mean Streets," and initially pictured Rocky as a "thuggish" character.

However, he went back to the drawing board for "Rocky" after a friend read the script and thought the boxer was too cruel for audiences to actually care about him. Stallone recalled her crying.

"She goes, 'I hate Rocky. I hate him. He's cruel. He hits people. He beats them up.'"

So Stallone thought about how to soften Rocky's character to make him more likable to viewers.

"I said, 'what if you stop short of it?' Like, maybe he almost did. He could have, that's his job, but he doesn't?' 'That'd be nice,'" he added. "I said, 'What if he had a girlfriend or something?' 'Yeah that's nice.' So I go back, start writing that: 'Girlfriend. Nice.'"