After his beginnings as a struggling actor for a number of years upon arriving to New York City in 1969 and later Hollywood in 1974, he won his first critical acclaim as an actor for his co-starring role as Stanley Rosiello in The Lords of Flatbush.
Stallone mostly only found gradual work as an extra or side character in films with a sizeable budget until he achieved his greatest critical and commercial success as an actor, starting in 1976 with his self-created role as the boxer Rocky Balboa, in the first film of the successful Rocky series (1976-2018). In the films, Rocky is portrayed as an underdog fighter that does battle with numerous brutal opponents, and wins the world heavyweight championship twice. The last two entries in the series are Creed and Creed 2, that serve as spin-off films focusing on Adonis Creed, the son of the ill-fated boxer Apollo Creed, whom the long retired Rocky is a mentor to. Reprising the role during the 2010s brought Stallone praise, and his first Golden Globe award for the first Creed, as well as a third Oscar nomination, having been first nominated for the same role 40 years prior.
Stallone had similar box-office success, portraying the PTSD plagued soldier John Rambo in the five Rambo films (1982–2019) and as mercenary Barney Ross in the three The Expendables films (2010–2014). He wrote or co-wrote most of the films in his three biggest franchises, and directed many of them too.
Stallone's film Rocky was inducted into the National Film Registry, and had its props placed in the Smithsonian Museum. His use of the front entrance to the Philadelphia Museum of Art in the Rocky series led the area to be nicknamed the Rocky Steps, and Philadelphia has a statue of his Rocky character placed permanently near the museum. It was announced on December 7, 2010 that he was voted into the International Boxing Hall of Fame in the non-participant category.
In 1977, Stallone was nominated for two Academy Awards for Rocky, for Best Original Screenplay and Best Actor. He became the third man in history to receive these two nominations for the same film, after Charlie Chaplin and Orson Welles.