Source of Inspiration: Threat

Horror films generally all have some kind of threat the characters face. This could be a creature, a human who is perhaps a serial killer, or even children. 

I will be making references to the following films:
The Awakening
Sinister
Paranormal Activity 4
The Resident
The Uninvited Guest
Ghost Ship

Ghosts
In the Awakening, a woman visits a boarding school after sightings of a child ghost were reported. Throughout the mystery of this story we are led to believe that the ghost mentioned is the threat to the characters.This shows that in horror films ghosts are often used, they are very effective as they can be combined with large, empty houses for example, giving a very isolated, scary location some paranormal life. Also, they are very effective because the characters do not always know if they truly exist  if they are present in the same location they are in themselves, and also can make the characters question themselves. For example, in The Awakening, Florence Cathcart is sent to expose a trick which is believed to be put on by the pupils. However, throughout the course of the film Cathcart begins to question what she believes and comes to the conclusion they might be real. 

Children (and being manipulated)
The Awakening also shows that in horror films, children are often used as the threat. This is because children are typically seen as very innocent and vulnerable  so when they suddenly become the threat, it makes it much scarier for both the viewer and the characters in the film, as they don't expect it, and don't want to believe it. It is also quite sinister in some cases as what the children do is often composed of mind games, which is worrying when they seem to have more capabilities and power than the adults of a situation. Evidence of this can also be found in films such as Paranormal Activity 4. 

In Sinister, there is once again the threat of children in the film which have been taken from their families, and it is later revealed they killed the rest of their families. This is very effective because throughout the film you are led to believe the real threat is a man/creature, making the reveal of the children actually playing a part in the deaths of their families much more chilling and as the name suggests, sinister. This also shows how in horror films children are often manipulated by something else, a greater force, showing their vulnerability and need for protection. Sinister is a great example of how a supernatural entity can cause havoc and ruin the character's lives as they are tormented by it. This is also an effective threat because it cannot be fully explained in the film, and this sense of unknown can cause the characters to unravel and lose their perspective on what is going on. 

Human Threat
In Ghost Ship, there is a combination of human threat and the threat of ghosts. In the film, the crew go against the passengers in an attempt to get the gold the ship carried. So they go about killing the passengers in different ways, such as poisoning them and slicing them in half. However later in the film there are the ghosts of the ship, Katie being one of importance as she is focused on at the beginning of the film. This once again links into how children are used in horror films. Ghost ship is a good example of how many different threats can be used in the same film, and it also shows how humans experiencing jealousy and greed can be the cause of much bigger problems for the characters in the film. 

In The Resident, a woman moves into a new apartment, but is then watched by her obsessive landlord, who has made secret tunnels around the apartment to watch her. This later turns into drugging her to rape her. This shows how effective human threats can be in a horror film, as they can make the film much more realistic and if there is a chance it could happen in real life, it makes the story very unnerving. This also shows how often the human threat is a man, who in some way manipulates a weaker woman. This shows how women are portrayed in horror films. 

Similar to The Resident, The Uninvited Guest is about a man who seems to disappear in some body's house after asking to use their phone. This once again is a very effective use of having a human threat in a horror film because it leaves the character to question himself and almost drives himself insane with worry. Again, the use of a man shows strength of the human threat, however it also shows that men can be portrayed as weaker in some films, as the 'victim' is a man in this film. Human threat is quite chilling especially in this film as you always wonder if you are being watched, and this creates a scary, uneasy atmosphere in the film. 

Overall, there are many different ways to portray some kind of threat in horror films, but human and children are probably most effective as they are very unsettling and go against what you want to believe is safe, such as an innocent child you would consider to be okay, in a horror film they could kill a character in the next scene. It allows for plot twists making the film gripping for the viewer.