Who or what is responsible for the success of a film?

Everyone and everything is responsible for success of a film.

Producer

Director

Writer

Singer

Production designer

Art director

Costume designer

Editor

Actors

Production equipments

Post-production like sound,edits,visual edits, sound effects,visual effects,sound breaking  colour grading and promotions also

It would be very unfair to simply say that only the names of the people which we on the screen after a movie ends are only responsible for the success of a film ,if i were to put thus thing to words i would simply put it like that -

the spot boy the ,makeup artist , even the tea boy or even the people such as the hair stylist,the stunt man,the sound artist and even the voice over artist and everyone along with the story-writter ,the producer the director and last but not the least the actor and actress are all together combindly resonsible for the sucess of a film.Beacuse  from where i see te success of a film truly depends on the tiniest and most minute efforts of all of these people.

HOPE MY ANSWER HELP YOU.