Movie make-up artists spent hours transforming Elijah Wood, left, and Sean Astin, right, into Hobbits for "The Lord of the Rings" trilogy.

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From Spock's ears in the "Star Trek" movies to Nicole Kidman's glowing beauty, and Harry Potter's scar to Hellboy's red facial prosthetic, all sorts of cinematic magic have relied on the skill and imagination of movie make-up artists.

Depending on the demands of the movie director and the script, a film make-up artist may need to be adept in creating sophisticated, high-fashion looks or need to rely on design, sculpting and creativity to alter an actor's looks by showing age, injury or characteristics of an alien or cartoon creature.

From the earliest days of the movies, make-up artists have had to combine their art with film-making technology. Actors in silent films, for example, had heavy yellow make-up to compensate for orthochromatic film that was insensitive to the red end of the light spectrum [source: Patrick Robertson].

Today, makeup techniques and computer-generated images come together to create visions like Lord Voldemort's snake-like face in "Harry Potter and the Goblet of Fire" (2005). For that look, make-up was applied to actor Ralph Fiennes' face in the usual way, but computer wizardry flattened his face and altered his nose [source: Internet Movie Database].

Behind the magic on the screen, the world of a make-up artist is a demanding one. But what exactly are make-up artists' responsibilities? What's it like to work as a movie make-up artist? And what does it take to become one? Read on to find out.