screenwriter; auteur
Refers to a person who writes film scripts, or more broadly a filmmaker with a strong personal creative vision (auteur). The auteur sense is more specialized and often used in film criticism.
As an auteur, he not only writes scripts but also directs.
That screenwriter has produced many masterpieces.
脚本家 is the more common and neutral term for a scriptwriter, while 映画作家 can imply a more artistic or auteur-like role.
Compound of 映画 (eiga, 'film') and 作家 (sakka, 'writer' or 'author').