10 Huge Movie Box Office Hits NOBODY Saw Coming

If you thought that the astronomical success of 1999's seminal found footage film The Blair Witch Project - which grossed $248.6 million against a shooting budget of just $60,000 - was a one-off, not quite.

Paranormal Activity was originally shot by filmmaker Oren Peli in his own home for a mere $15,000, and after premiering at the Screamfest Horror Film Festival in 2007, eventually made its way into the hands of Steven Spielberg, leading Paramount to acquire distribution rights and plan a modest theatrical release.

Paranormal Activity launched in September 2009 in just 12 US cinemas. Because each of these screenings sold out, Paramount rapidly expanded the film's release both domestically and around the globe, with it opening wide just two weeks later.

By the end of its run, this microbudget found footage romp had netted an awesome $194.2 million - almost triple that of the considerably higher-profile horror sequel Saw VI released shortly after.

Paranormal Activity's unthinkable commercial performance made it one of the most successful films of all time in terms of cost-to-profit ratio, leading to an inevitable glut of sequels which have collectively grossed almost $900 million on a total $28 million budget.