Rocky (1976)
John Avildsen's 1976 boxing underdog launcher. Began the franchise that defined boxing cinema.
Sylvester Stallone wrote Rocky in a few days and refused to sell it unless he could star, turning down substantial offers while nearly broke. The film won Best Picture and he was nominated for both acting and screenwriting, which almost nobody has done.
He wrote or co-wrote most of the Rocky sequels, the Rambo films, Cobra and the Expendables series, and the writing is consistently underrated because the performances are what people discuss.
Rocky’s script is genuinely well constructed. The fight is not the point and he does not win it.