Years before Twilight had werewolves and vampires at each other’s throats, there was 2003’s Underworld. The film opens in the midst of a war between vampires and Lycans (a.k.a. werewolves) that has been raging for centuries. Selene (Kate Beckinsale), a vampiric Death Dealer charged with killing any Lycan she finds, discovers that the werewolves are after a human named Michael Corvin (Scott Speedman). As she attempts to figure out what, exactly, the werewolves want with a human, Selene discovers that all is not as it seems with this war—or even her own past. Should she abide by vampiric rules, or defy them in order to protect the man she loves?

Underworld was a surprise hit: It was made for approximately $22 million but grossed nearly $96 million, kicking off a film franchise that brought in nearly $550 million over five movies. Ahead of its 20th anniversary, here’s what you should know about the film that started it all.

1. The idea for Underworld was Blade Runner meets The Howling meets Romeo and Juliet.

Underworld began when Len Wiseman—who had previously done prop work on film and TV and directed music videos—took a meeting with a studio about directing his first feature film. They wanted a werewolf movie. Wiseman took that idea to his friend, actor and writer Kevin Grevioux, but neither one of them was really excited about it.

As they were talking it out to see what kind of pitch that they could come up with, Grevioux suggested crossing Blade Runner with The Howling—as he put it to the Los Angeles Times, “A guy who goes after werewolves in a city.” Then he suggested throwing in a dash of Romeo and Juliet, with “werewolves on one side and vampires on the other. Make it like Montagues versus Capulets, and we deal with them on that level.”

Grevioux said Wiseman initially was initially skeptical, but he eventually came around. “You think it's going to be so cheesy,” Wiseman told the LA Times, “but then if you think about it, if they let us do it the way that we want to it would be kind of cool.”

Grevioux whipped up a rough story, and then Wiseman called stunt performer-turned-screenwriter Danny McBride (The Outer Limits) to help flesh it out. “When I came aboard, the three of us started from scratch,” McBride recalled. “Instead of werewolves, it would be [Lycans], because we hated the term werewolf. It has a cheesy connotation, because so many terrible movies have been made.“

The trio used Romeo and Juliet as “a template from which to formulate a pitch and illustrate our high-concept idea,” according to Grevioux, but it wasn’t Underworld’s only inspiration. “Thematically, the inspiration was a little more real, and I have to say more tragic,” he said in an interview with Skewed and Reviewed. “And that’s the experiences I’ve had with interracial dating and different biracial children I had come in contact with over the years. It’s amazing the hatred that’s hurled at you because you may date someone from another race. It’s almost as though man has learned absolutely nothing about brotherhood in the past 50 years.”

2. The story’s roots are scientific.

Many of the traditional rules around vampires and werewolves don’t fly in the Underworld universe—the movie’s vampires can see their reflections in mirrors, for example, and the Lycans can transform at will, not just during a full moon. “I have a background in genetic engineering,” Grevioux said. “Given that, I wanted to take a different approach to the werewolves and vampires in this film. I wanted to use science as a basis rather than mysticism. I created a virus which was the reason why vampires and werewolves became what they had finally become.”

3. Selene was inspired by a comic book character.

Grevioux, a huge comic book fan, told Coming Soon that “The model for Selene was the psychic vampire of the Hellfire Club in the X-Men comics—the Black Queen Selene.”

4. Halle Berry could have played Selene.

In 2017, the Underworld Facebook page revealed that Halle Berry had been “considered” to play Selene. Kate Beckinsale ultimately nabbed the role, and Berry would go on to don a skintight black costume of her own in 2004’s Catwoman.

5. Director Len Wiseman’s storyboards convinced both Kate Beckinsale and Scott Speedman to sign on.

In the early 2000s, Beckinsale was known mostly for period films and romantic comedies, and she wasn’t much of a horror movie fan—so she was inclined to pass on Underworld when it came to her in a batch of scripts. “At first I thought this would mean wearing a gingery wig and a long nightie and doing lots of screaming and garlic eating, so I wasn’t that interested,” she told the BBC in 2003. But Wiseman’s script came with storyboards of the action, and that changed her mind: “When I saw the drawings that the director had done, I realized that it was a very cool and very slick action movie.”

Beckinsale was a big action movie fan, but lamented the fact that in most action movies, women are either away from the main action or, if they are the leads, the films themselves are campy. “What really appealed to me about this,” she said in a making of feature, “is that [Selene] could have been a guy. And I think that was really fresh and interesting. And then I had to pull it off.”

The drawings also stuck out to Speedman, who was just coming off the hit TV series Felicity. “I remember being not sure about going in for [Underworld],” he told Vulture in 2023. “I hadn’t read the script yet, and attached to the script were Len Wiseman’s drawings. I could see how his visual style was just off the charts. It really felt like a commercial hit to me, like, Wow, this could really have a chance to do something, especially with the budget they were trying to do it at.”

6. Speedman had some concerns about playing a werewolf.

After Speedman nabbed the role of Michael—the human the Lycans are pursuing, who is bitten and becomes a werewolf—he called Wiseman with a few concerns. “I was like, You’re not gonna make me roar, are you? Like some sort of Lycan?” the actor told Vulture, laughing. “That terrified me, that I was gonna have to do all this basically animal work on set. … But Len had this point of view of what he wanted to do and walked me through all that stuff.”

Which isn’t to say that he got out of roaring altogether: “We went to the creature shop to get fitted for our teeth,” Beckinsale explained, “and they made us, for the photos, roar. I was so horrified, and Speedman was even more horrified than me.” (Neither one of them has to roar in the actual movie, though the werewolves do.)

7. Beckinsale described her costume as “a condom with sleeves.”

Selene’s black latex outfit was apparently pretty comfortable, though initially Beckinsale had some reservations about the costume (which she compared to “a condom with sleeves”). “In Budapest it goes from hot to winter in like one day, there’s no changeover,” she said. “The first week it was boiling hot … and I was dreading the whole movie. Because I was like, peeling this thing off when I was through with it. It was sweaty and it would just take ages. And then it got freezing and it was fine.” One part of the costume was more troubling than the rest, though: “Any shot running with the coat was a nightmare,” Wiseman recalled.

The teeth also proved to be challenging. “I remember all of us … madly negotiating those teeth for the first time and it took about, you know, three or four days,” Beckinsale said in DVD commentary. There were two sizes of fangs: A smaller set for everyday, and a larger set for fight scenes.

8. Beckinsale didn’t actually do the jump in the movie’s opening scene.

Underworld opens with some exposition about the werewolf-vampire war delivered as Selene perches high above a city in a gothic building … then leaps from it. “That was really from an actual building that high [and the filmmakers] didn’t think it was safe for me to do that,” Beckinsale said. “I did the landing, but they did it in a couple of different shots.” (You can see exactly how they pulled it off in the making of documentary here.)

One stunt she did do, assisted by wire, was leap over a werewolf—and she was proud of herself for having done it, because once she saw how it was going to be shot, “I just thought that was too risky. ... I’m like, ‘It’s completely dangerous! The camera is far too close and the walls are close together and there’s sharp corners. I could hurt myself easily.’”

9. Mythbusters tested one of Underworld’s scenes.

In her attempt to figure out why the Lycans are after Michael, Selene heads to his apartment, where she confronts him—and ends up having to fight off a bunch of Lycans. To escape, she shoots up the floor around herself until it gives way, taking her to the hallway below. “I cried after this,” Beckinsale revealed in DVD commentary, because of shrapnel. “I literally got, like, glassed in the face. … As it was going on I was thinking ‘Please don’t let me be registering the fact that this really hurts.’”

Fun fact: The Mythbusters tested whether what’s shown in this scene would be possible—and pretty much busted it. After 360 rounds and a few blasts from a shotgun, they weren’t any closer to going through a wooden floor.

10. David Bowie could have had a cameo.

Wiseman really wanted to get musician David Bowie into a scene of a vampire gathering. Unfortunately the schedule didn’t have much wiggle room, so it didn’t happen. “It was a time factor,” Wiseman said in DVD commentary. “We heard later, I think we heard, that he would have been interested.”

There are some other cameos of note, though: Screenwriter Danny McBride shows up in a scene as the vampire Mason, and you can see Wiseman’s hands loading ultraviolet bullets into a gun in another scene. Grevioux, of course, has a much larger role as Raze—and yes, that really is his voice.

11. Beckinsale asked for the sex and nudity to be axed from the script.

Beckinsale wanted to make sure Selene came across as the true heroine of the movie, not just a sex object—and to accomplish that, according to UPI, she asked for sex and nudity to be removed from the film. “I find the latex suit and the very shiny bottom takes care of a lot of things,” she said. “I think there was an issue with the scene where she got in the shower, which I nixed very early on. I just feel like in Die Hard, you don't get that kind of shot of Bruce Willis.”

12. Bill Nighy was in the makeup chair for six hours.

In the Underworld mythology, the vampire coven is ruled by three elders—Viktor, Amelia, and Marcus—who have a power-sharing arrangement in which one rules for a hundred years, awakens the next elder, and then goes into hibernation mode for 200 years before being awakened to start the whole thing over. Bill Nighy played Viktor, one of the heads of the coven who Selene awakens out of the cycle because she suspects that another vampire in the coven, Kraven (Shane Brolly), is up to no good.

Nighy apparently had the toughest makeup on the entire film: In order to pull off the appearance of a vampire who had been asleep for a century, he had to spend six hours in the makeup chair every day. (And that was after enduring the long and uncomfortable process of having his head and body molded for prosthetics.) “Unspeakable,” he told the BBC of the process. “No one will ever be allowed to do any of that stuff to me again, as long as I live. I had absolutely no idea what they had in mind. I thought there’d be a zip up the back, but it was a medieval process.”

Nighy also did a lot of his own fight scenes at the end of the film, and according to Beckinsale, “he said he’d never even done a stage fight.” Wiseman added, “We beat the sh*t out of him too, he was just exhausted … He never put his hands up and said ‘It’s too much.‘” Nighy called his Underworld role “the high point of my action career.”

13. Not ruining a take by laughing was Nighy’s biggest challenge.

According to Nighy, what made the Underworld shoot especially difficult was all the hissing he had to do. “I enjoyed being a vampire, it was fun,” the actor told GQ. “The great challenge is keeping a straight face because it involves a lot of hissing. … And, if you’re doing that to another man in his face, it is hard not to laugh. As soon as anyone would say ‘cut,’ the crew would just fall apart.”

14. Many of the werewolf effects were practical.

Underworld committed to doing many of its creature effects practically. The werewolves were designed by Patrick Tatopoulos (Independence Day, Venom) and consisted of foam latex body suits and stilts constructed specifically for each performer. There was a separate head (complete with yak hair inserted strand by strand) that had a face controlled using animatronics, which moved the lips and muzzles. A video feed inside the head allowed the performers to see, and a comms unit let the puppeteers communicate with them so they could do things like roar on cue. It took four people to operate each werewolf, but it was worth it: “Our werewolves could walk down the street and people would run screaming,” producer Richard Wright said in a making of doc.

The werewolf transformations, however, were done digitally: First the actors were filmed going through the motions against a green screen. Next, they filmed a person in a werewolf suit against the green screen. Visual effects artists combined those elements with scans of the actors and the head to create a transformation morph. “I was really happy with how [the transformations] turned out in the end because I wanted them to be shaky, and look painful,” Wiseman said. “I didn’t want it to be smooth. I was actually telling the guys to try to make the transformation look as much like an animatronic effect as possible.” Some practical effects did end up being replaced by CG shots, including the scene where werewolves land on top of elder Amelia’s train car—the practical version looked too silly.

Beckinsale revealed in an interview with the BBC that she wouldn’t have signed on if her character was a werewolf: “Did you notice that there were no lady werewolves? I don't think America is ready for hairy women. But playing a werewolf wouldn’t have been half as much fun. It looks a bit painful, to be honest.”

15. They struggled with the design of the hybrid.

In Underworld, the werewolves are on the hunt for a human directly descended from the first true immortal, whose blood will allow them to combine the werewolf and vampire bloodlines, creating a hybrid creature, which turned out to be a major challenge.

Wiseman said in a making of featurette that the half-vampire, half-werewolf hybrid was “conceptually … probably one of the most difficult things to design—we actually stressed about it quite a bit.” Early concepts looked a bit like Buffy the Vampire Slayer’s vamps, which he didn’t want. Another concept that Wiseman drew showed the hybrid covered in short hairs—which Wiseman described as “like the nose hair on a cat.” But that was easier said than done: “The only way to do that is this process called flocking, which I guess you basically have to put electricity inside a person’s body to have the flocking stick to a person’s skin,” Wiseman said. “[Patrick had] never done it on a human, and he said … ‘I think it’s just an impossible process, and a dangerous process to do.’” They eventually decided to give the hybrid the skin texture and coloring of a werewolf and changed the musculature so that it was different than the other creatures in the film.

16. Wiseman had to fight for Lucian’s backstory.

Werewolf Lucian (Michael Sheen) is originally presented as Underworld’s bad guy, but it’s later revealed that hundreds of years in the past, he (and the rest of the werewolves) were enslaved by the vampires. Lucian and Viktor’s daughter fell in love, and in order to preserve the vampire bloodline, Viktor had his own daughter killed—and forced Lucian to watch. It was a backstory that Wiseman had to fight for.

“I like the idea of presenting this bad guy and you have a complete change of heart for [him],” Wiseman said in DVD commentary. “We had to fight … Early on, when we were going through a lot of the story development, there was a push to keep Lucian just a full-on bad guy.” Instead, Lucian got his backstory, which is one thing that turns Viktor from ally to enemy in Selene’s eyes.

17. The ending went through some changes.

In Underworld’s climactic final scenes, Selene (spoiler alert!) confronts Viktor about the fact that he had killed her family and lied about it—something he had previously blamed on the werewolves. The screenwriters actually changed the dialogue in that scene the night before; no one wanted to tell Nighy on the day of shooting, but according to Beckinsale, “he was totally cool. He liked it better.”

Another change that was made at some point was to the movie’s ending. “In the first draft, Selene actually doesn’t kind of save the day, which you kind of brought to our attention when we first met,” Wiseman said in DVD commentary, to which Beckinsale responded, “Seemed a bit of a shame.” In the final version Selene does, in fact, save the day.

18. Some people accused the filmmakers of ripping off The Matrix.

In DVD commentary, Wiseman spoke about how both critics and people online called the film a ripoff of The Matrix (1999) because Selene, like The Matrix’s Trinity, wears a black latex suit. “What am I gonna put a vampire in,” Wiseman said, “fuschia?” It wasn’t just the outfit, though: Critics called out similarities between the sets and special effects, too, and also drew comparisons to films like The Crow.

When asked about it at the time, Beckinsale said, “If you do a cop movie, there’s so many cop movies, and they all kind of look the same. Maybe you go, ‘Well, that kind of looks like Ransom.’ You know, like nobody ever says that. But there’s only a few movies, really, that stylistically look this way. So, you’re going to get compared to The Crow, you’re going to get compared to The Matrix, you’re going to get compared to a few things like that. There’s only a few around, so I don’t really worry about that.”

19. Underworld sent Roger Ebert down a Google rabbit hole.

Legendary movie critic Roger Ebert did not have a lot of great things to say about Underworld, ultimately concluding that “It’s so impossible to care about the characters in the movie that I didn’t care if the vampires or werewolves won.” But the movie did apparently make him curious about the rules of werewolf transformation. “Michael, a young intern who is human, at least until he is bitten by a werewolf—and maybe even after, since although you become a vampire after one bites you, I am uncertain about the rules regarding werewolves,” he wrote. “Hold on, I just Googled it. A werewolf bite does indeed turn you into a werewolf, according to a Web site about the computer game Castlevania, which helpfully goes on to answer the very question I was going to ask next: ‘What would be the result if a werewolf bites a vampire? It is called a were-pire or wolf zombie …’”

20. Underworld spawned four more movies.

Underworld: Evolution came out in 2006 and picks up right where Underworld left off, with Selene and Michael on the run. The third movie, Underworld: Rise of the Lycans (2009), is a prequel running through events featured in the first film and showing how the werewolf-vampire war kicked off, with Michael Sheen and Bill Nighy reprising their roles, and Patrick Tatopoulos making his directorial debut. Next came Underworld: Awakening (2012) and Underworld: Blood Wars (2016). “I think I envisioned it coming to an end after the first one,” Beckinsale said in 2016. “I never really planned on doing four movies playing the same character. And it’s an amazing privilege because there’s not that many girls that get the opportunity to be in a long-running franchise, especially an original story.”

While more Underworld films aren’t necessarily out of the question, it seems like Beckinsale’s participation is: “I wouldn’t return,” she told Variety in 2018. “I’ve done plenty of those.”

This article was originally published on www.mentalfloss.com as 20 Fascinating Facts About ‘Underworld’.