I believe the creator has the biggest impact on the industry. They are the ones creating the book; they are the ones creating the story. Without them there would be no comic, and in several modern instances there would not be a “movie representation.” There are many popular movies that are based off of comic books. There are even some cartoons based off of comic books. Where would these be without the creator?
One example of a popular movie that would not be around is Superman. There have been several movies that have come out over the years that were based on this legendary comic. There was also a cartoon show about him, Smallville, and even some really weird things, like the Krypto the Superdog cartoon. If the creators had never dreamed Superman and Clark Kent up none of these would exist.
Another example is G.I. Joe. The movie recently came out, personally I enjoyed it, and it was based off of the comic books and the cartoon. Transformers one and two have both come out and they have a history that includes comic books, cartoons, and a lesser known Japanese cartoons, toys, and comics. The League of Extraordinary Gentlemen is another comic based movie. The ever popular V for Vendetta, Watchmen, X-Men, Ironman, Blade, Teen Titans, Green Arrow, and many more were all based off of comic books (if you would like to see a list feel free to go here: http://www.comicbookmovie.com/comic_book_movies/).
Some of the Comics that either have or have not become movies have become actual books (literature). The Transformers and G.I. Joe moves each have their own books. There are a few Japanese Manga that have become novel series, like Fullmetal Alchemist.
None of these things would be possible without the creator. Yes, there needs to be someone to publish it and whatnot, but without the creator the comic doesn’t exist.