Visualises stories using sketches on paper. quick pencil drawings and marker renderings are two of the most common traditional techniques, although nowadays flash, photoshop and specialist storyboard software applications are being used more often.

They are called story board artist

Explanation:

This are people who work wit advertisement companies and film producers by sketching scenes of movies in order for actors and directors to have an insight of the actions of scenes play out during meeting, they also edit scenes of movie as it progresses.