Horror is one of the rare genres where a movie's budget doesn't necessarily dictate it's quality. The only tools required by aspiring filmmakers are: suspense, fake blood, and a whole lot of ingenuity. In come cases, thinking on the fly means enlisting some atypical expertise. Occasionally, these professionals come together and create something so memorable, so chilling, that the very thought of it sends shivers up your spine.

Here are ten of those memories in Screen Rant's 10 Movie-Making Facts You Need To Know About the Scariest Horror Films.

Poltergeist (1982)

The eighties were a weird time: people wore spandex, Duran Duran ruled the airwaves, and human skeletons were cheaper than plastic ones. In 1982 when Tobe Hooper was directing Poltergeist he found that out.

A pivotal scene in the film features actress JoBeth Williams bobbing around in a muddy pool with skeletons as torrential rain hammers from above. The use of real human skeletons for this scene fueled superstitions that the set was cursed, as several people died during production. Human or non, Williams was less concerned about the bones, and instead focused her worries on being electrocuted. Taking place in a pool during a storm, the scene relied on many different electronics, all of which could have fallen into the pool at any point, killing Williams.

In an act of solidarity (and to ease her anxiety), producer Steven Spielberg (who is rumored to have directed much of the film) got into the water with the actress and pointed out that if a light fell, at least they’d both die.

Saw II (2005)

Focused around a killer named Jigsaw, the Saw series became famous for the elaborate Rube Goldberg-esque traps the killer sets for his victims. One of our favorite traps is also one of the most unsettling for many.

The franchise’s second installment, aptly named Saw II, contains a sequence in which a key is buried in a pit of used syringes. After being thrown into the pit, actress Shawnee Smith scrambles rabidly to find it, and is stabbed with dirty needles all over her body. The props department used 60,000 real needles, and took over four days to replace their metal tips with softer fibre optic ones, and then were painted to appear used. Several others were attached to foam under Smith’s shirt, giving the illusion that they were stuck to her torso.

After discovering sixty thousand needles wouldn’t be enough to pull off the scene, the team ordered another sixty thousand and padded the bottom of the trap to make it look even fuller.

Halloween (1978)

The next tidbit on our list comes courtesy of John Carpenter’s 1978 indie-slasher, Halloween. After murdering his sister when he was only a child, the film’s resident psychopath, Michael Myers, was committed to a sanitarium. After 15 years in the clink, Meyers escapes, terrorizing the town with a series of grisly murders.

Perhaps the most recognizable icon from the film is the mask worn by the killer as he stalks his prey. When it came time for the crew to produce the mask, they approached several experts, but were all turned away due to the film’s modest budget. Thankfully, they found some inexpensive inspiration in the form of a $1 Star Trek James T. Kirk mask. After some modifications were made and the mask was painted, the team found it to be so unsettlingly creepy and emotionless that it was used in the film and it’s sequels.

Carrie (1976)

High school is a traumatic time for a lot of teenagers, but it’s safe to say that Carrie (Sissy Spacek) had it the worst. Growing up with a strictly religious mother and no real friends, she was deserted.

At prom, a malicious group of students play a cruel trick on Carrie. They rig the system, and vote her to be Prom Queen. Winning, she makes her way to the stage to accept her new title. While basking in her moment of acceptance, Carrie has a bucket of blood poured on her, much to the amusement of everyone watching.

The shot took 2 weeks and 35 takes to get right. Despite actress Sissy Spacek’s willingness to have real blood dumped on her for the scene, the crew used a mix of karo syrup and food coloring, which became sticky under the heat produced by the lighting. Spacek was undeterred by this, and even slept in her bloody clothes for 3 days to preserve the continuity of the scene.

Scanners (1981)

Telekinetics and telepathists have been portrayed many different ways on the big screen, but David Cronenberg’s might be the scariest. In 1981, he wrote and directed Scanners, a film about warring groups who have the ability to not just read minds, but control them as well.

With an ability known as “scanning,” the protagonists could make someone’s head explode if they wanted, and luckily for the audience, that’s exactly what they do! After fiddling around with wax and ceramic moulds, the effects department struck gold. Using a hollow gelatin replica of the actors’ head, the team filled it with fake blood, gelatin chunks, and leftover food, then proceeded to blast it with a shotgun from below. The end result is a messy, bloody explosion that is satisfying to watch, each and every time.

Hostel (2005)

Chances are if you’ve seen a scary movie, or any episode of The Walking Dead, you’re already familiar with the bloody work of Greg Nicotero. As a man with well over one hundred credits to his name, Nicotero is one of the industry’s most talented special effects makeup and prosthetic artists. Not one to shy away from a grueling scene, Nicotero was a natural choice for the 2005 Eli Roth gore-fest, Hostel.

Inspired by stories of “kill vacations” in which tourists can pay to torture someone to death, the movie is full of terrible violence seldom seen elsewhere. One scene in particular shows the mangling of a woman's face, and required 150 gallons of fake blood. In fact, Nicotero’s work was so nauseating for audiences, there were several reports of people fainting, vomiting, and having heart attacks while watching it in the theater.

The Birds (1963)

Alfred Hitchcock is nicknamed The Master of Suspense, and anyone who’s seen the 1963 classic The Birds understands why. Set in Bodega Bay, California, the movie centers around the murderous birds who terrorize it’s residents. They attack indiscriminately, and often gang up on their victims when they least expect it.

While certain types of birds like hawks, gulls and parrots can be trained to perform on command, crows are a finicky bunch. In place of training, the birds on set were fed a heavy diet of wheat and whiskey to keep them on the ground.

In the film’s cruel final attack, actress Tippi Hendren becomes swarmed by birds. This one scene took seven days to film, and was so hard on Hendren that she was given a vacation after it was complete. The sequence required that live birds be attached to her clothing with strands of nylon so they couldn’t fly away. After spending a week like that, anyone would need a vacation.

Sinister (2012)

Moving into a new house is a good way to wipe the slate clean and begin a new chapter of life, which is exactly what Ellison Oswalt (Ethan Hawke) does in 2012’s Sinister. While exploring the new pace, Ellison happens across a box of snuff films depicting the grisly murders of the house’s previous occupants.

One film in particular, “Pool Party ’66” is mentioned by writer C. Robert Cargill as being especially difficult to shoot. Not only was it challenging to keep the super 8 camera dry, the stunts were all completely manual. The actors were really tied to their chairs, and really pulled underwater, resulting in more than a few close calls for the performers. The movie’s demon, Mr. Boogie (Nick King) can be seen standing at the bottom of the pool, an effect achieved by strapping weights to his body, with a safety diver never far away.

Night of the Living Dead (1968)

When Night of the Living Dead was released in 1968, audiences were taken aback by its blood and gore. Being filmed in black and white was very advantageous to the effects department, allowing them to transform everyday foods into terrible and disgusting props. The main ingredient used on set?

Chocolate sauce. The human limbs being ingested on screen were really made of ham, and then covered with chocolate, much to the disgust of any actor tasked with eating it. In one famous scene, actress Kyra Schon is seen stabbing a woman with a gardening tool as blood spatters all over the wall. In reality, Schon was thrusting the trowel into a pillow while an offscreen crew member flung chocolate syrup at the backdrop. The audio was recorded separately and then sync'd during post-production.

Conclusion

Of course, every movie goes through it's fair share of twists and turns during production, and the crew is there to answer the challenge, no matter what. There are so many beloved horror movies out there, and lots of them have amazing scenes because of the determination of the people behind the camera, who are sometimes lost in the shuffle of the films they create. With so many iconic scenes to choose from, it's hard (and perhaps unfair) to narrow it down to only ten, so we're counting on you to tell us about your favorites in the comments below.