Freddy Krueger has become among the most notorious villains in horror history. While you’ve probably seen the films plenty of times, here’s a few bits of trivia you probably didn’t know about the series.

1. Wes Craven’s original concept for Freddy Krueger was considerably more gruesome, with teeth showing through the flesh over the jaw, pus running from the sores, and a part of the skull showing through the head. Make-up artist David B. Miller argued that an actor couldn’t be convincingly made up that way and a puppet would be hard to film and wouldn’t blend well with live actors, so these ideas were eventually abandoned.

2. According to Robert Englund, he based the physicality of Freddy on Klaus Kinski’s performance in Werner Herzog’s Nosferatu the Vampyre (1979). Englund also says on his DVD commentary that in his mind, the back-story for Freddy was based on something from his own childhood. On Valentine’s Day when Englund was in school, everyone in the class made Valentine cards for one another, but there was one boy who received no cards from anyone. Englund theorized that this boy went on to become Freddy.

3. The inspiration for the character of Freddy came from several sources in Wes Craven’s childhood. Fred Krueger was a schoolmate of Craven with whom he had shared a paper route, and who had bullied him for several years. In The Last House on the Left (1972), Craven also used this experience as inspiration, calling the villain Krug. Freddy’s appearance (especially the dirty clothes and hat) was inspired by a hobo who Craven saw staring at him through his window one day when he was ten.

4. The scene where Nancy (Heather Langenkamp) is attacked by Freddy in her bathtub was shot using a bottomless tub, which was put in a bathroom set that had been built over a swimming pool. During the underwater sequence, Langenkamp was replaced with stuntwoman Christina Johnson. Langenkamp spent 12 hours in the bath during filming.

5. In a deleted scene featured on the Laser Disc and VHS from Anchor Bay we learn that Nancy and many of her friends from the neighborhood weren’t always only children, but had a brother or sister before they were killed by Freddy (during the scene in the basement just before Nancy’s mother reveals she has Freddy’s glove.)

6. An omen that Johnny Depp’s character is about to die occurs as he is laying in bed listening to his radio. The broadcaster announces, “It’s midnight and you’re listening to station KRGR.” KRGR can be interpreted as meaning “Krueger.”

7. The sparking glove effect seen throughout the movie was achieved by attaching the glove to a car battery. The famous scraping noise was created by scratching a steak knife on the underside of a metal chair.

8. In relation to the famous red and green sweater, in the script, the sweater was red and yellow (based on the colors worn by Plastic Man, who, like Freddy, could change his form; the idea was that whatever Freddy changed into would be yellow and red). However, when Craven read an article in Scientific American in 1982 that said the two most contrasting colors to the human retina were red and green, he decided to alter the colors.

9. The scene of Tina (Amanda Wyss) thrashing across the ceiling was shot using a rotating room set which was slowly spun to allow her to role into position. The camera was bolted to the wall, and the cameraman strapped into a chair beside it, which turned in tandem with the room. For the two shots where Rod (Jsu Garcia) and Tina reach for one other as Tina is on the ceiling, she is really lying on the floor and Garcia is upside down with his hair pasted down to stay flat. The effect was so good that just before shooting began, Amanda Wyss got a bad case of vertigo.

10. The idea behind the glove was a practical one on Wes Craven’s part, as he wanted to give the character a unique weapon, but also something that could be made cheaply and wouldn’t be difficult to use or transport. At the time, he was studying primal fears embedded in the subconscious of people of all cultures and discovered that one of those fears is attack by animal claws. Around the same time, he saw his cat unsheathe its claws, and the two concepts merged, although in the original script the blades were fishing knives, not stake knives as in the finished film.