Not all aliens are created equal. If worse came to worse, I’m pretty sure I could take E.T. in fight. The same goes for that bitch Mac, from Mac and Me. On the other hand, if you put me in the ring with a Predator, he’d be using my skull as trophy in five seconds flat.

Because the threat posed by extraterrestrials can vary so greatly, we’ve compiled this list of nine aliens you don’t want to eff with. After all, throwing water on the alien from Signs is a fun way to spend an afternoon, while doing the same thing to a Xenomorph is a really bad idea.

Superman (Superman)

Because the Man of Steal likes to wrap himself in the flag, people forget that he’s not from the good ol’ U.S. of A. In fact, he’s not even from Earth. Regardless, this son of Krypton is nearly invincible, which makes him one of the last aliens you should mess with.

Alien Abductors (Fire In the Sky)

Fire in the Sky isn’t a great movie. Considering the film is about an alie abduction, there is a notable lack of alien abduction. But when the film finally deals with the topic, it makes for some terrifying scenes. The aliens look more like grotesque humans than creatures from another world, which makes them uniquely frightening. And the fact that they have no qualms about performing medical experiments without anesthesia seals the deal.

ID4 Aliens (Independence Day)

On the one hand, the aliens from Independence Day are pretty lame. After all, one punch from Will Smith will knock them out. But considering their technology allowed them to destroy every major city on the planet, we’re classifying them as “not to be messed with.”

Klingons (Star Trek: The Motion Picture)

I’ve never trusted Klingons, and I never will. I can never forgive them for the death of Kirk’s boy. These physically imposing warriors like to kick ass and take names. Take Worf, for example. Does he look like someone you should mess with? I thought not.

Optimus Prime (Transformers)

Few things are more badass than a big rig. Optimus Prime, a giant robot from another planet who disguises himself as a big rig, is defiantly one of them. While the Transformers movies might suck, this iconic character does not. Bumblebee, on the other hand, does.

The Bugs (Starship Troopers)

Nobody likes bugs. Well, almost nobody. Buffalo Bill from Silence of the Lambs liked those moths, but I digress. In Starship Troopers, the film's heroes are forced to deal with bugs from another planet. Oh, and they’re humongous. A can of Raid isn’t going to cut it.

The Thing (The Thing)

How do you mess with an alien if you don’t even know it’s there? This is the problem posed by the Thing, a parasitic creature that takes on the appearance of its victims. The other problem: it’s capable of assimilating the entire planet in three years, should it ever reach civilization. Best not to mess with this thing.

The Predator (Predator)

Chances are you’ll never even get the opportunity to mess with a Predator. The best you can hope for is that the Predator will choose not to mess with you. A large humanoid creature from a warrior culture Predators are known not only for their physical prowess, but also their advanced weaponry. Unless you’re a trained commando or Danny Glover, you don’t stand much of a chance against these creatures. But if you do manage to fight hard enough, you might just win their respect.

The Xenomorph

Was there any doubt that the Xenomorph from the Alien franchise would be at the top of the list? Even the Predators have a hard time dealing with these remorseless killing machines. They’re quick, fearless, and in the right conditions, they breed like cockroaches. Unfortunately, your body could end up as part of the breeding process. Oh, and by the way, if you do manage to cut or shoot one of these things, you’ll have to worry about the acid runing through its veins. Good luck with that.