10 Great Horror Movies That Started Out As Short Films

In 2013, Swedish director David F. Sandberg released Lights Out, a three-minute flick about a woman being stalked by a creature that is only visible in the dark. 

This micro-movie was created for the Bloody Cuts Horror Challenge film festival and it won Sandberg the Best Director gong. More importantly, it became a massive hit on YouTube, which prompted the Hollywood vultures to swoop in.

Three years after his short premiered, Sandberg had transformed Lights Out into a full movie. This version of the film followed a similar premise, but went into much more detail, tying the existence of the shadow creature into one of the characters' trauma.

Despite its controversial ending, Lights Out was a huge success, raking in nearly $150 million at the box office. Not bad for something that began as a sub-five-minute festival entry. 

In a nice touch, the actor from the original short, Lotta Losten, was given a small cameo in the feature.