This year, audiences flocked to features by filmmakers who cut their teeth on online shorts, like Curry Barker ( Obsession ), Kane Parsons ( Backrooms ) and Markiplier ( Iron Lung ). But they follow in the footsteps of David F. Sandberg, whose 2016 Lights Out was the first studio-backed horror movie to originate as a YouTube short. The Swedish native’s two-and-a-half-minute film starred his wife, Lotta Losten, as a woman stalked by a mysterious figure when the lights go out. After making the short on virtually no budget, Sandberg entered it in the Bloody Cuts Horror Challenge, winning best director. Months later, a Reddit post linked to it, page views skyrocketed from 8,000 to more than a million and Hollywood came calling.

The couple credits the short’s global appeal to its lack of dialogue: “It just floated around the world because I don’t say anything,” Losten tells THR . Sandberg heard from producer Lawrence Grey, who wanted to collaborate with James Wan on a big-screen version.…