It's the whole production team. No one is bigger than the team.
Sure, but the problem is that, too often in the Hollywood feature industry, writers are treated as smaller
than the rest of the team, as disposable, interchangeable contractors who are granted no control over the process. Their contribution to the collaboration is undervalued, and that's why we get so many movies that are superbly directed and acted and photographed and edited and scored and VFXed and so forth, but have lousy dialogue and characterization and incoherent plots. Look at George Lucas and M. Night Shyamalan -- both excellent technical filmmakers, great with visuals and stylistic stuff, but they insist on writing their own scripts and thereby severely undermine the quality of their own films, because they aren't good writers. And the industry is set up in such a way that this keeps happening.
Hopefully this is starting to change as more writer-producers and writer-directors who come from television, like Abrams and Whedon and Judd Apatow, become prominent filmmakers. But it'll take time.