Who was writer of rocky film?

In the film Rocky (1976) the director was: John G. Avildsen.

In the film Rocky II (1979) the director was: Sylvester Stallone.

In the film Rocky III (1982) the director was: Sylvester Stallone.

In the film Rocky IV (1985) the director was: Sylvester Stallone.

In the film Rocky V (1990) the director was: John G. Avildsen

In the film Rocky Balboa (2006) the director was: Sylvester Stallone