Pretty Woman, My Best Friend's Wedding, Notting Hill, and Runaway Bride were all smash rom-com hits delivered by the one and only Julia Roberts in the decade of the 90s. Some of the biggest blockbusters of the era, these films made Roberts one of the most bankable stars in the history of cinema at the turn of the millennium. But, did you know that she was also very successful in thrillers as well? With entries like Flatliners, Sleeping with the Enemy, The Pelican Brief, and Conspiracy Theory, the megastar cashed in quite a bit in the dramatic genre, too, and starred opposite some of the industry's most serious actors.

Even though it's the hugely successful rom-com that she is widely remembered for, let's take a look at some of the films that rightfully earn Julia Roberts the title of 90s Thriller Queen.

Julia Roberts Followed the Success of 'Pretty Woman' With 1990 Thriller 'Flatliners'

When Roberts took on the role of medical student Rachel Mannus in the Joel Schumacher-directed Flatliners in August 1990, she was riding high on the success of her breakout performance in Pretty Woman. That certainly didn't hurt the box office numbers of the film, but it was also the actress' first turn in a very dark and ominous movie about a group of medical students who dabble with near-death experiments to see if they can get a glimpse of what lies beyond this life.

Starring alongside Kiefer Sutherland and Kevin Bacon, Roberts more than held her own in a group of young actors who were still finding their way in Hollywood at the turn of the decade. Her portrayal of Rachel is earnest and grounded, delivering some memorable moments in the bleak and suspenseful thriller that showed audiences immediately that she was far more than a one-trick pony.

'Sleeping With the Enemy' Was One of the First Films to Address Domestic Abuse

A year later, Roberts doubled-down on the serious side of things and delivered a terrific performance opposite

Patrick Bergin in the very important film Sleeping With the Enemy. In 1991, few films had addressed the horror of domestic abuse the way that this heart-pounding thriller did. Based on the 1987 Nancy Price novel of the same name, Sleeping With the Enemy is a serious reality check about an overprotective, controlling, and jealous husband who goes to extreme lengths to keep his wife under his thumb. Roberts is very convincing as Laura Williams Burney, a woman paralyzed by fear who grows more terrified of her domineering husband Martin (Bergin) as he begins to gaslight and psychologically abuse her while also threatening physical harm if she doesn't stay in check. Sleeping With the Enemy was a drastic departure from anything Roberts had done in a blossoming career and once again showed that she had almost limitless range as a performer. Her role in the film resonated with audiences to the tune of $175 million at the box office on a budget of just $19 million, clearly showing that Roberts could be successful outside of the rom-com genre. Sleeping With the Enemy was also an impactful movie in that it brought the very serious issue of abuse and sociopathic narcissistic behavior out of the shadows in an era when it wasn't being explored and exposed enough.

Julia Roberts Joins the John Grisham Adaptation Craze in 'The Pelican Brief'

In the mid-90s, it seemed like every other thriller movie being produced was an adaptation of the wildly successful and prolific law thriller novelist John Grisham, beginning with The Firm and ending with The Rainmaker. All of Hollywood's heaviest hitters were nabbing parts and cashing in on the taut legal thrillers that Grisham was churning out almost yearly. So Roberts decided that she wanted to get in on the mix as well by starring in

The Pelican Brief as Darby Shaw, a law student who writes a brief that incriminates some very important players in the deaths of two Supreme Court justices and finds herself in the crosshairs of deadly assassins while trying to expose the plot behind the murders. This was the first real action thriller for Roberts where we got to see her play cat and mouse games alongside co-star Denzel Washington as she must literally run for her life in order to stay alive long enough to get to the bottom of the plot. And again, Roberts is up to the task of giving the audience an exhilarating and captivating performance in a film that is both smart and super amped up on adrenaline from beginning to end.

Julia Roberts Conquers the Psychological Thriller in 'Conspiracy Theory'

In 1997, Roberts starred opposite Mel Gibson (in what was a powerhouse duo at the time) in the taut political psychological drama, Conspiracy Theory directed by Richard Donner. Roberts plays a lawyer at the New York Justice Department who befriends an oddball taxi driver who has some off-the-wall ideas about all manner of government secrets and conspiracies. She humors him only because Jerry (Gibson) had previously saved her from a mugging, but generally doesn't take him very seriously, and she shouldn't.

But when she finds herself in the middle of an investigation involving the death of her father, she becomes a little more open-minded about one of Jerry's theories that proves to be much more than the paranoid ravings of an eccentric blue-collar cab driver. Roberts delivers another fantastic performance as she jumps head-first down a rabbit hole that will put her and Jerry's lives at risk. Roberts has always been like a chameleon with her uncanny ability to rise to the occasion and give memorable performances that fit the part she's playing. But despite her versatility, all of her roles have one thing in common — she takes the viewer on a ride where for at least a couple of hours, you can suspend any disbelief you have about the larger-than-life Hollywood star and settle in for a satisfying and thrilling experience.