Commissioning editors (film and TV )
They commission promising writers and look for best new writers and people to bring forward for the development of the film. They also look at treatments and sort out the good stuff which might have been quite difficult for this movie as the treatment was consisting of 90 pages.
Producers
The producers provide the budget for the movie and make sure everything happens on time and within the budget and usually well known producers are used for such big movies.
Directors
The directors dos the creative role in the movie and are in overall control of the film. They also provide some sort of visual for the film.
Script editors
They edit the script to ensure that the dialogue works in the entire production and I think they had a really major role in this production as the script was rewrote for a while even during filming and also characters' lines were switched and given to other characters since the original book was rather sexist since it was written in a time where men where above women so there were mainly male characters and so some female characters needed to be added.
Agents( film and TV )
They seek work for people to cast as characters in the books as well as technical crew.
Writers
They write the story for the movie or production.
Notes from the adaptation of the Lord of the rings video
Peter Jackson (director), broke down all 3 books that were written by Tolkein into a 90 page treatment. He then sent the 1st screenplay to Miramax but they wanted to be 1 film so he went elsewhere to get funding for the movie. It was then sent to New Life but it saw it as 2 films so 2 screenplays had to be re-written.
The whole production took 15 months to shoot and rewriting of the script carried on even during filming.
Had to sort of write a new script as the original book was rather sexist since it was written in a time where men where above women so there were mainly male characters and so some female characters needed to be added and that is where Phillipa (a friend to the director) was brought in and she mainly handled the female roles and romantic scenes in the movie since she was a massive fan of the books and wanted to turn them into a movie.
During script writing, characters' lines were switched and given to other characters and actors were also involved in the writing of the script as they were asked about what made them laugh, what they thought the character might do for example: Frodo playing or handling the ring.