For Hollywood, heroism is skin-deep.

Facial scars have long been a staple of the villain in literature and even more so in movies – think Scar in “The Lion King” or any number of James Bond baddies.

But filmmakers also use scars, often an actor’s real nicks and knock-abouts, to convey a troubled hero.

Take “Lord of the Rings: The Fellowship of the Ring,” for example. Actors Viggo Mortensen and Sean Bean portray two members of the heroic fellowship. Both have prominent facial scars in real life, but only Bean’s is visible in the movie.

“As the heroic Aragorn, Viggo has his scar almost completely hidden in his beard,” said Vail Reese, a San Francisco dermatologist who analyzes skin conditions in the movies on his Web site, Skinema.com.

“In Bean’s case, however, his character, Boromir, is on the edge, moving toward the dark side – and his scar is not hidden,” Reese added.

Reese pointed out that when Mortensen has played a villain, as in “A Perfect Murder,” the actor’s upper lip scar is obvious – even highlighted.

Conversely, when Bean has played a romantic leading man, as in 1997’s “Anna Karenina,” the scar above his left eye is difficult to spot.

Hiding Mortensen’s scar may have been just being faithful to J.R.R. Tolkien’s literary description of Aragorn as a bearded man. There’s no mention of a scar for Boromir in the original novels, however.

“How much they unconsciously noticed it, I can’t say, but I do wonder if, when they were casting the actors, they didn’t look at Sean and, on some level, think about that scar,” said Reese.

Whether or not Bean’s souvenir from an on-set accident during the filming of “Patriot Games” helped land him the role of Boromir, a scar symbolizing conflict in a hero is not a Hollywood invention.

“In some folktales, the hero becomes physically branded,” said Shakespeare scholar Miranda Johnson-Haddad, who has studied the depiction of villains.

“In the case of Boromir, it works beautifully – he is definitely a conflicted character,” she said. “You see the scar and you assume he got it honorably in battle, but it also indicates there’s something a little off with him.”

Boromir isn’t the only hero with issues and a scar.

Character actor Tommy Flanagan, severely scarred in a knife attack, has made a career of playing complicated but heroic sidekicks, including a vengeful warrior in “Braveheart.”

Laurence Fishburne, who has facial scars, has also played a few not-so-good good guys, most notably Morpheus in “The Matrix.”

“Laurence has got impressive scarring that’s played up much like Sean Bean as Boromir in ‘Lord of the Rings,’ ” said Reese. “And for most of the movie you’re really not sure if he’s a bad guy or a good guy.”

– Gemma Tarlach