9. Special Templates Were Used To Draw It Onto Daniel Radcliffe's Forehead
While the first movie was being developed, the placement and design of Harry's scar was a heavily-debated topic.
With its importance as both a visual point of interest and an integral plot device, getting it right from day one was crucial. However, early on, the filmmakers were faced with a problem: in the books, the scar is often mentioned, but its exact position on Harry's forehead is never disclosed.
Quotes like "under a tuft of jet-black hair over his forehead they could see a curiously shaped cut, like a bolt of lightning" from The Philosopher's Stone didn't give any hints, and so the filmmakers had to go directly to Rowling for an answer. "Razor sharp, just off center”, was the response she gave to director Chris Columbus.
With the scar's placement set, the conversation turned to making it look as neat and realistic as possible. To accomplish the look you see onscreen, special templates - almost like small helmets that would wrap around Radcliffe's head - were used, and the scar was stencilled on. Whenever Harry was under any Voldemort-related duress, the makeup team would redden the scar to make it look more prominent.