by Tom Bishop
BBC News Online entertainment staff
Freddy Krueger, the chilling killer from A Nightmare on Elm Street, finally comes face-to-face with Jason Voorhees from Friday the 13th in a new film, Freddy Vs Jason, out on Friday.
Freddy Krueger (left) and Jason Voorhees have become horror icons
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In a summer of cinema sequels, Freddy Vs Jason is the only one with two mass murderers as its lead characters.
Jason first appeared in 1980's gory Friday the 13th, then lurched his way through nine sequels.
Meanwhile, Freddy stalked teenagers in their dreams for 1984's A Nightmare on Elm Street, his razor glove terrorising them for a further six films.
But they are not the only two fictional murderers to become cult film icons.
We are also on first-name terms with Michael Myers (Halloween), Hannibal Lecter (The Silence of the Lambs) and Damien (The Omen).
But why do such bloodthirsty characters attract such a loyal following?
Hannibal Lecter was recently voted the top screen villain of all time
"They do the kind of thing that we wish we could," says Tony Timpone, editor of US horror magazine Fangoria.
"We wish we had the power of Jason to take out the bullies at school, or the cleverness of Freddy to outwit our co-workers. They appeal to the dark side of the movie-goer."
While horror films are aimed at impressionable teenagers, Dr David Weeks - a consultant clinical neuropsychologist at the Royal Edinburgh Hospital - is not convinced the fans identify with the killers.
"Only a minority - between a quarter and a third of the audience - choose such negative role models," he says.
"If you genuinely start aspiring to be the murderer you are obviously well on the way to becoming psychotic yourself."
This is supported by research which suggests that on-screen violence is most likely to influence viewers already predisposed to aggressive behaviour, he says.
"People don't just watch these films because they love the killer," Dr Weeks adds. "There's an aspect of voyeurism, the camera lingering as it finds each victim.
"Horror movies also put us through a wide range of emotions from fear to disgust, and a need to escape."
Mr Timpone says the challenge for film-makers is to create a compelling storyline between the killings.
"It is also important for these films to have a wicked sense of humour, to make them more palatable. Otherwise you are just left with a bloody mess."
Freddy Vs Jason producer Sean S Cunningham says his iconic anti-heroes represent "the faceless, unnamed fears" in our psyche.
"Each of them has become a symbol of all those things that collectively we are afraid of, first as teenagers and then as adults," he explains.
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Escaped psychopath Michael Myers was similarly described by Halloween director John Carpenter as "an irrational, unstoppable force of evil" while Damien was literally the anti-Christ.
When demonised in this way, the horror villain becomes strangely comforting.
"By seeing a face put to evil on the big screen it helps us deal with uncertain evils in the real world, such as a mysterious terror organisation or unknown bomber," says Mr Timpone.
"People might get a kick out of all the gory darkness in these films, but ultimately they want to see the villain defeated and the world set straight by the end."
Strength and cunning
Superhuman killers also force heroines such as Nancy in A Nightmare on Elm Street, Sidney from Scream or Jamie Lee Curtis' Halloween baby-sitter to draw upon hidden reserves of strength and cunning.
"We cannot admire heroes unless they face and conquer such strong adversaries," Dr Weeks says.
"In this respect, modern horror films follow ancient storytelling tradition.
"Othello's villain Iago was also presented as purely evil but emerged to be more complex than that. In fact villainous characters often prove to be the most interesting."
With Freddy Vs Jason expected to spawn even more sequels, movie murderers look likely to haunt us for some time to come.