Sometimes, when novels and comics are adapted into movies, filmmakers take liberties with one aspect or another of the production, in an effort to create something that doesn’t alienate fans or casual viewers. Sometimes these changes are necessary for numerous reasons, such as: a particular novel may be too long, and scenes may require cutting if it’s to fit the running time allocated; or characters as written don’t work in the film’s context.
When that happens they may be removed all together, or perhaps re-written as composites of various other characters that didn’t exist in the original source material.
This approach is also used with comic-based films, with varying degrees of success. For example, anyone that has read the X-Men comics noticed immediately that the costumes vaguely, if at all, resembled those from the comics. This was probably done because the filmmakers believed that the costumes worked for that particular milieu, but wouldn’t translate outside of it.