Debate Club: The 5 biggest surprise hit horror movies

Welcome to Debate Club, where Tim Grierson and Will Leitch, the hosts of the Grierson & Leitch podcast, tackle the greatest arguments in pop culture.

Some of horror's biggest hits were hardly surefire propositions at the time. Depending on the cinematic era, maybe horror was stuck in a commercial tailspin. Or perhaps the filmmakers were pushing the envelope, testing the limits of what an audience could handle. Or maybe the movie was made on the super-cheap, its cast and crew never thinking they were about to revolutionize the genre.

Whatever the reason, sometimes to make your mark you have to do what no one's expecting — and do it really well.

For this week's Debate Club, we look back at five surprise horror smashes. This list is a good reminder: A lot of classics started out as a roll of the dice.

How surprising was The Purge becoming a massive franchise that may outlive us all? How about the fact that it launched at Colorado's short-lived Stanley Film Festival to very little buzz? Or that the rare critics who bothered to review The Purge there almost all dismissed it? Or that it basically announced the arrival of Jason Blum and Blumhouse as major players? Or that it was so long ago that it seemed like junk just because Ethan Hawke — hardly hot in 2013 — was the lead in it?

The crazy thing now is that "the Purge" has become part of our regular lexicon. It feels like it was always there.

Legend has it that Steven Spielberg, who had an early DVD copy of Paranormal Activity at home, was so freaked out by the movie that he brought the film back to his studio office in a garbage bag.

Not since The Blair Witch Project had a found-footage horror flick been so effective at scaring the hell out of you. And remarkably, Paranormal Activity achieved these terrors through the simplest means — simply point a camera at a room and watch as the ghosts invisibly start to wreak havoc.

The simplicity was the secret to a franchise that's produced six installments — with a seventh apparently in development — and even a Japanese spinoff. The acting may never have been top-notch, but that was also part of the charm: We never doubted the ordinariness of these poor bastards, whose home lives were suddenly nightmarish.

Hopes were high after Get Out's initial trailer, which made the film look more unhinged and lunatic than it actually was. But even the rosiest expectations could have never seen what was coming: $176 million in grosses, a Best Picture nomination (and Screenplay win for Jordan Peele), and the launch of a whole new era of prestige horror.

And coming as soon as it did after the 2016 presidential election, it seemed to capture a terrifying new moment in American history perfectly.

From the beginning, when director William Friedkin put the kibosh on the studio's desire to have Marlon Brando play Father Merrin — can you imagine, by the way? — all the suits were nervous about The Exorcist. It was too "Satanic," too intense, too much. Even the critics weren't initially crazy about it.

But The Exorcist became a phenomenon in theaters almost immediately, to the point that some news reports at the time wondered if the movie was actually a public health hazard. And it ended up being Warner Bros.' most successful film ever up to that point, surpassing My Fair Lady!

The film's backstory is almost as riveting as its scares. When The Blair Witch Project premiered at Sundance, audiences didn't know it was fictional, assuming they were watching actual footage from a group of documentary filmmakers who went out into the woods and were never heard from again. But even if you knew the conceit, this found-footage landmark created a terrifying and exciting new way to experience horror.

Directors Daniel Myrick and Eduardo Sánchez ended up delivering one of 1999's biggest hits — it made more money than would-be blockbusters Wild Wild West and The World Is Not Enough — and although the sequels and reboots never caught fire, the original still stands as proof that ingenuity and skill can mean more than a big budget.

Grierson & Leitch write about the movies regularly and host a podcast on film. Follow them on Twitter or visit their site.