20 HUGE Hit Movies NOBODY Saw Coming

8. Paranormal Activity

In the more than quarter-decade since The Blair Witch Project, only one horror film has well and truly replicated its rags-to-riches success story, and that's Paranormal Activity.

The found footage film was made by director Oren Peli for just $15,000, after which it was acquired by DreamWorks and later Paramount, who spent an additional $400,000 on a new ending and polishing the film in post-production.

Paranormal Activity began its extremely limited theatrical rollout in September 2009, almost two years after the original version started its festival run, and strong word-of-mouth resulted in consistent sell-out screenings, prompting Paramount to slowly expand it to more locations.

Eventually demand was enough that Paramount released Paranormal Activity wide, where it went on to gross a basically unimaginable $194.2 million, making it one of the most profitable films in the history of Hollywood in terms of return-on-investment.

As a basically no-budget movie with not a single name actor in it, for it to mop the floor with so many of the year's biggest movies - including its most direct competition, Saw VI - was a totally impossible result in the weeks prior to release.