The Dark Knight Joker's scars were inspired by a terrifying trend that has also hit football culture

Facial scarification has long been a part of Joker lore, dating all the way back to the character's creation in 1940. It's well known that the Joker was inspired by Conrad Veidt's character from the 1928 film 'The Man Who Laughs'. The character, Gwynplaine, was accosted by hoodlums as a child, and a smile was permanently etched on his face. The scarification trend continued in the 1989 film "Batman," which saw the Joker undergo botched cosmetic surgery.

The prosthetic supervisor on "The Dark Knight" was Oscar nominee Conor O'Sullivan ("Saving Private Ryan," "X-Men: First Class," "Hatching"). In the Empire article, O'Sullivan explained that his mission was a bit open-ended; he knew the Joker needed scars, but received no further instructions. He said:

"I was never given a concept or a reason for the scar before I started designing the Joker's scars. Once I realized it would be scars rather than a frozen smile, I immediately thought of the punk and skinhead era and some unsavory characters I had met in those days. The terminology for this type of injury is a Glasgow or Chelsea smile."

He immediately remembered meeting someone with a Glasgow smile and decided to emulate that look:

"My references had to be real. A delivery of slot machines was made to the estate near my workshop and the man who delivered them had a Chelsea smile. I had the courage to ask him for a picture and he told me about how he got his scars from being involved in a 'dog fight.'