10 Biggest Unsolved Mysteries In Famous Horror Movies



  • Horror movies often leave big, unsolved mysteries, like the violent bird attacks in Alfred Hitchcock’s “The Birds” or the origins of the entity in “It Follows.”
  • Many horror movie mysteries are never explained, like who Billy is in “Black Christmas” or what really happened to the Engel family at the end of “Krampus.”
  • The unexplained mysteries in horror movies add to their terror, leaving audiences with unanswered questions, like the origin of the monsters in “Bird Box” or the true identity of the Blair Witch in “The Blair Witch Project.”



While many horror movies tell complete stories, there are many others that have left some big, unsolved mysteries. It’s not uncommon for horror movies to end on cliffhangers that never pay off as they don’t expand with sequels, nor is it surprising for them to have plot twists that, more often than not, only make the story more confusing. Even in franchises with many sequels, like Halloween and Friday the 13th, there are various unsolved mysteries that no sequel, prequel, remake, or expanded media has taken the time to address.

In many cases, the unsolved mysteries in horror movies are the result of events that happen before the movie begins that aren’t explored, with the characters only dealing with the consequences of these. In other movies, the big mysteries are all about the origins of the villains, which in many cases add to what makes them so terrifying. While some of these mysteries in horror movies can still be solved at some point, either in sequels or if the creators open up about them, there are many that can’t be answered anymore, making way for theories that look to offer an explanation.

10 Why Did The Birds Go Crazy In The Birds?

Directed by Alfred Hitchcock

Melanie running from birds in The Birds

Alfred Hitchcock’s 1963 horror classic The Birds follows Melanie Daniels (Tippi Hedren), who upon arriving at Bodega Bay, notices the birds (all types of them) acting strangely. The birds suddenly start attacking and killing people, and Melanie and company have to find a way out of town and to a safe place. However, throughout The Birds, a reason for the birds becoming violent and deadly isn’t given, but it has been theorized that it was the result of some chemical, algae, or something more abstract, such as the birds wanting revenge against humans.

9 What’s Up With Martin In The Killing of a Sacred Deer?

Directed by Yorgos Lanthimos

Barry Keoghan eats spaghetti in The Killing of a Sacred Deer

The Killing of a Sacred Deer is the story of Steven Murphy (Colin Farrell), a cardiac surgeon who spends time with 16-year-old Martin Lang (Barry Keoghan), whose father was a patient of Steven and died years earlier. Things turn uncomfortable when Steven meets Martin’s mother and Martin demands more attention, and it’s later revealed that Martin has a very sinister plan: to “balance things” for his father’s death, Steven now must kill either his wife, daughter, or son within a few days or they will all die after becoming paralyzed, refusing to eat, and bleeding from the eyes.

Martin was right, and the Murphys begin to suffer all that and Steven is forced to kill one of them. The big mystery in The Killing of a Sacred Deer is how Martin managed to make all that happen, implying that he had powers or cast some sort of curse, but it’s unknown exactly how he did it.

8 Who’s Billy In Black Christmas?

Directed by Bob Clark

billy peeping his eye in black christmas 1974

Black Christmas follows a group of sorority sisters who, during the Christmas season, start receiving threatening phone calls from a mysterious stalker, who then starts killing the young women. The big twist in Black Christmas is that the killer is hiding inside the house, but who exactly Billy is is never explained. The murderer’s face isn’t shown, either, with only his eye shown as he observes his victims. It’s completely unknown why Billy targets the girls, where he comes from, and who he really is, which makes him a terrifying presence in Black Christmas.

The 2006 Black Christmas remake gave Billy a whole backstory of abuse and violence.

7 What Happened To The Engel Family At The End Of Krampus?

Directed by Michael Dougherty

A young boy opening up his gifts in Krampus

Krampus follows the dysfunctional Engel family, who, after Max (Emjay Anthony) loses his Christmas spirit due to his family’s squabbling, unleashes the wrath of the demonic beast Krampus, known for punishing naughty children at Christmas time. After Krampus attacks the family and kills many of them, Max apologizes to him and offers himself as a sacrifice, but Krampus still throws him into a fiery pit.

Max then awakens in his bed on Christmas and finds his family alive and well downstairs, but when he unwraps a present that’s revealed to be Krampus’ bauble, the family slowly remembers what happened and their house is shown to be inside a snow globe as part of Krampus’ collection. It’s unclear if this is hell or purgatory and why Krampus kept his victims in snow globes.

6 Where Are The Monsters From Bird Box From?

Directed by Susanne Bier

Blindfolded Sandra Bullock in a boat in Bird Box

Based on the 2014 novel of the same name by Josh Malerman, Bird Box centers on Malorie Hayes (Sandra Bullock), a pregnant woman who, along with other people, does her best to protect herself and her unborn child from mysterious and monstrous entities that cause people to kill themselves every time they look at them. Bird Box doesn’t explain where the creatures come from and only focuses on the consequences of their presence on Earth, and even though the mystery of their origin makes them scarier, it’s the movie’s biggest unsolved mystery.

Bird Box got a Spanish spin-off sequel titled Bird Box Barcelona, streaming on Netflix.

5 Is The Witch Real In The Blair Witch Project?

Directed by Daniel Myrick & Eduardo Sánchez

Heather Donahue in the woods in The Blair Witch Project

The Blair Witch Project follows three filmmaking students – Heather, Mike, and Josh – who go into the Black Hills forest near Burkittsville, Maryland, to film a documentary about the local myth of the Blair Witch. Once there, they quickly experience strange events, such as getting lost in the woods, sticks snapping at night, the laughter of children heard at night, and stick figures hanging from trees around their tents. The first of the group to disappear is Josh, and at the end of The Blair Witch Project, Mike is seen standing in a corner facing the wall while Heather is taken by an unseen force.

Aside from the mystery of what truly happened to Heather, Mike, and Josh is the big question of whether the Blair Witch was real or not, as it could have all been in their heads or it could have been another paranormal event that led to their disappearances.

Related: The Blair Witch Project Secretly Used Time Travel – Theory Explained

4 What’s The Origin Of The Entity In It Follows?

Directed by David Robert Mitchell

Maika Monroe in a pool in It Follows.

It Follows is the story of Jay Height (Maika Monroe), who after a sexual encounter with her then-boyfriend, is pursued by a supernatural entity. This entity can take the appearance of any person and can only be seen by those affected by the “curse”, and if it catches the person, it kills it, and moves on to the one who passed the curse to them.

To make it even worse, the entity can’t be killed or defeated, and those affected by it can only buy themselves extra time by having sex with more people to pass it on. Although it’s clear what the entity represents, within the world of It Follows it’s unknown where the entity comes from, what it really wants, and how the curse started.

3 Is Bludworth The Grim Reaper in Final Destination?

Directed by James Wong

Final Destination William Bludworth at the morgue

Final Destination follows Alex Browning (Devon Sawa), who cheats death after a premonition of a catastrophic plane explosion, but Death later starts taking the lives of those who were meant to die on the plane. When sneaking into a funeral home to examine his friend’s corpse, Alex and Clear (Ali Larter) meet mortician William Bludworth (Tony Todd), who tells them about Death’s plan. Bludworth returned in Final Destination 2 and Final Destination 5, where he continued to share his knowledge about death and offer advice. Due to his sinister presence, Bludworth has been speculated to be either Death or the Grim Reaper, but neither has been confirmed nor denied.

Tony Todd will reportedly reprise his role as William Bludworth in Final Destination 6, which can finally put an end to this mystery.

2 What Did Anna Whisper At The End of Martyrs?

Directed by Pascal Laugier

Bloody woman looking scared in Martyrs.

Martyrs follows Anna Assaoui (Morjana Alaoui), who, in an attempt to rescue a tortured woman, is captured by a secret society led by a woman referred to as Mademoiselle (Catherine Bégin). This secret society seeks to discover the secrets of the afterlife through the creation of “martyrs”, for which they capture young women and subject them to all types of torture. Anna reaches the “final stage” and survives being flayed alive, and while in an “ecstatic” state, she whispers something into Mademoiselle’s ear, who later kills herself. Martyrs doesn’t reveal what Anna whispered to Mademoiselle, so there are different theories about it, such as Anna saying that heaven exists or that there’s no afterlife.

1 Who Was Infected At The End of The Thing?

Directed by John Carpenter

Kurt Russell as MacReady in The Thing.

The Thing follows a group of American researchers in Antarctica who come across the title creature, an extraterrestrial life-form that assimilates and imitates other organisms. This creates paranoia, fear, and uncertainty among the group, as they no longer know who is human and who is the “thing”. At the end of The Thing, survivors R.J. MacReady (Kurt Russell) and Childs (Keith David) sit down and share a bottle of Scotch whisky, leaving open to the audience’s interpretation which one of them was human and who was the “thing”. The popular “eye gleam” theory has been debunked by Carpenter, who claims to be the only one who knows who’s the “thing” at the end, and it doesn’t seem like he will ever share the truth.