Anyone whose parents read them The Ugly Duckling as a child knows one you shouldn’t judge people by the way they look. In fact, children are bombarded with this message all the time. The ugly duckling is a swan. The beast in Beauty and the Beast has a heart of gold. Gaston’s the real beast! Movies, in their post-modern moments, have even self-referentially twisted the concept around in movies like Shrek. The beautiful princess Fiona, in a subversion of the fairytale princess, is actually happier as a kindly troll, and Shrek himself has many layers, like all ogres. Of course, adults need a reminder of this too, and John Merrick, the man saddled with extreme deformities in The Elephant Man, serves as a tragic reminder that we care more about looks than we care to admit.

The interesting phenomenon here is that we have to learn this lesson at all. We all know intellectually that Steve Buscemi’s unusual countenance tells us nothing about his character. We all know that Johnny Depp [Glamour Magazine UKs 89th Sexiest Man of 2017] and his rugged good looks didn’t keep him from being an abusive husband. And yet our culture is full of these cues. Of course, in general, modern media is careful not to rely too heavily on them. It’s rare to find a modern movie in a realistic setting where a hideous villain is battling a handsome hero. The influence is still there, though. How many movies can you name where a hideous protagonist battles a handsome villain that I haven’t already mentioned?

Despite the partial prohibition on this kind of association, though, there is at least one genre where associating looks with character traits is still par for the course: science fiction. The Fifth Element serves as a near perfect example of this phenomenon. Let’s start with Leeloo [Milla Jovovich], the alien who’s entire body is a weapon for vanquishing the great evil that’s set to bring death to the universe. The savior of the universe isn’t some creature covered in tentacles. It’s not a furry blob with three arms and a weird sucker for a mouth. No, in a staggering display of self-aggrandizement on the part of humanity, the film casts a human who was at one time the highest paid model in the world as the ultimate antidote to evil. Human beauty is equated with moral perfection.

Of course the film also has a couple of other good aliens in addition to Leeloo. First, there’s the Diva Plavalaguna [Maïwenn], the opera singer who helps defeat the great evil by holding the stones required to activate Leeloo’s powers. This character, other than her exotic blue skin and an unusual skull, is also essentially a fashion model. In fact, I wouldn’t be too surprised to see someone dressed like Plavalaguna strutting down the catwalk at Paris Fashion Week next year. Interestingly she [I assume] looks like a cross between the noble inhabitants of Na’vi in Avatar and Oola, one of Jabba the Hut’s dancers, at least to my human eyes. While we don’t get to see much of Oola in Star Wars, I’m sure she was a good and upstanding citizen of the empire.

And then there’s the Mondoshawans, the alien guardians of the weapon to defeat the great evil. Unlike Leeloo and Plavalaguna, the Mondoshawans don’t look like fashion models. Instead, though, they bear a resemblance to an armored cartoon duck. This appearance, combined with the way they walk, gives the Mondoshawans an appearance that suggests that they’re both friendly and tough. In fact, I can’t help but think of Friar Tuck, the famous battling friar from Robin Hood. In many ways, they occupy the same role that a Wookiee or an Ewok might in the Star Wars universe.

The visual motif is even clearer when we come to the alien villains of the film: the Mangalores. How might one describe the Mangalores? Hairless dogs with fish lips? Bipedal worms with shriveled elephant ears? They actually remind me of a particularly unpleasant man I had the displeasure of working with for a couple of years. How ever you describe at them, it’s unlikely that you’re going to think of them as friendly or beautiful. If you were to stick the wrinkled visage of a Mangalore in front of any stranger and ask them if the character were a hero or a villain, I’m pretty confident they’d come up with the correct answer. And sure enough, they spend their time in the film thuggishly murdering and pillaging their way towards the apocalypse.

Of course, The Fifth Element is far from the only film that relies on ugly villains. Emperor Palpatine from Star Wars essentially looks like a zombie; the Predator looks like he’s in terrible need for a visit to the dentist; the Xenomorphs from Alien have mouths inside of their mouths; and the aliens from Independence Day are what happens to squid when you send them to Doctor Moreau.

Why do we continue to use this shorthand so often with aliens in science fiction when we don’t in most other genres? While there’s no definitive answer, there are a few factors that certainly push movies in this direction. First of all, with aliens, creators are given a high level of freedom to change the appearance of a character. No matter how a film chooses to alter a human character, the creator is anchored by the need for him to look human. In addition to the lack of visual constraints, there are also fewer social constraints attached to equating ugly aliens with unfavorable moral stances. Imagine the backlash against a movie featuring a strong association between people with a certain physical disfigurement and evil, for example. Or, for that matter, imagine if, time after time, that same disability was used to signal a person’s villainous nature. While one hopes that people aren’t tempted to represent people this way, even if they were, movie studios, when it comes to mainstream movies at least, want to avoid controversy. They have a strong incentive to avoid offending people. Repeating this thought experiment with alien features, though, there’s no such constraint. If floppy eared aliens are going to be associated with evil, who’s going to stand up for aliens with floppy ears? No one. And then, finally, associating aliens with their character and behavior just works. Would Alien be nearly as scary if it featured a fluffy villain with big doughy eyes? While I would love to see that cut of the movie, I’m betting it wouldn’t be considered a horror classic. When you combine these three factors together, it’s no surprise that we see this shorthand used over and over in science fiction films. We may be taught not to judge other by their appearance, but apparently in space, all bets are off.