10 Best Movies With An Unseen Enemy

7. Paranormal Activity

Though the Paranormal Activity franchise eventually flamed-out amid relentless annualised releases and a patent lack of imagination, the original 2009 movie remains a fantastically unnerving example of how to engineer tightly-wound tension with limited resources.

The film's big success is that, despite focusing on a couple who find themselves terrorised by a demonic entity in their home, it never once shows the audience what the creature looks like.

The devilishly simple execution sees director Oren Peli exploiting the invisible fears that keep us all up at night - creaking hallways, doors gently moving on their own and ambient noise that sounds a hell of a lot like footsteps.

The closest we ever get to seeing the demon is a series of powdered footprints it makes in their bedroom, with the film otherwise using subtle and virtually cost-less tricks to manipulate the environment.

The result was strong critical acclaim and a stonking $193.4 million box office haul against a mere $15,000 budget.

Sadly, though, the final film in the series, Paranormal Activity: The Ghost Dimension, decided to dispense with the little remaining mystery and reveal what the demon looked like. It wasn't good.