The world of Pokémon is constantly growing. What started out as 151 has grown by leaps and bounds, adding a slew of colorful characters with each subsequent release. We've been on some amazing adventures over the years and conquered some truly vibrant regions. For the most part, Pokémon is a wholesome and happy experience.

That said, there is a darker side to the Pokémon universe. We've seen plenty of creepy fan theories and discussions about elaborate Pokémon wars. Underneath the smiling facade is a spooktacular world, filled to the brim with horrifying things, alarming legends, and visually terrifying creatures.

Some Pokémon are more unsettling than others. In fact, a lot of these Pocket Monsters have rather morbid and mysterious Pokédex entries. This led us to compile a list that points out some of the creepiest creatures to ever grace the series. Some of these Pokémon thirst for blood, while others feast on dreams. Whether it's visual horror, mental torture, or an overall eerie feeling, these creatures are potential nightmare fuel.

Did your favorite Pokémon make the list? Which one scares you the most? Let us know!

15 Parasect

At first glance, something seems a bit off about Parasect. It could be the fact that this crab-stuffed mushroom is a three-foot tall insectoid. That's enough to make anyone's skin crawl, but for us, Parasect's real fear factor lies in those haunting white eyes. There is something so demonic about those soulless orbs.

A quick skim through the Pokédex explains why Parasect goes from adorable little bug (Paras) to alien-like monstrosity. This is where things get even creepier. According to Pokémon lore, when evolving, the fungus on Paras' head grows so large that it takes control of the evolved form. Those blank white eyes represent a zombified state. The mushrooms do all the thinking for Parasect, using it as their insectoid host.

14 Yamask

Full disclosure, this is one of the creepiest Pokémon to ever grace the Pocket Monster universe. We have no idea what developers were thinking when they placed this morbid creature into a children's game. Yamask looks strange on its own, but we wouldn't classify it as visually horrifying. It has an almost Egyptian aesthetic, with a stylized eye and it carries around a golden colored mask.

Like Parasect, the Pokédex sheds light on the true origins of this seemingly innocent Pokémon. Apparently, Yamask was once a human. We know, that claim has been made many times before with a variety of different Pokémon, but with Yamask, it's 100 percent canon. According to the Pokédex, the mask it carries is the face it had when it was a human being. Sometimes it even looks to the mask and weeps. That's right, every time you catch a Yamask, you're actively enslaving a human soul.

13 Hypno

This one is a bit self-explanatory in a sense. Hypno looks rather human in design: in fact, it has five fingers on each hand (including thumbs). Its feet are beastly, sporting only three large toes on each foot and it's covered in a dense yellow fur. Hypno is visually unsettling, especially so when you notice its 5-foot 3-inch height. It always carries a mysterious pendulum with it, which it uses to place its prey into a deep sleep.

Hypno primarily feasts on dreams, which is creepy enough in its own right. However, according to a Pokédex entry in Pokémon X, this hypnosis Pokémon will occasionally kidnap its victims. The journal entry is alarming, stating that there was an "incident in which it took away a child it hypnotized." Another Pokédex entry, from Pokémon Moon, suggests that the creature carries off anyone who's having a good dream.

12 Victreebel

This large bell-shaped plant Pokémon was modeled after the Pitcher Plant, which lures unsuspecting prey and then traps them in a sticky liquid. Victreebel's appearance is a bit exaggerated, with two large fangs poking from its mouth and a gaping maw which lay hidden beneath a leafy protrusion. This makes it the ultimate foe for any unsuspecting bug Pokémon.

The truth is, you should always be on the lookout for this frightening flora, no matter who (or what) you are. According to lore, Victreebel lures prey with a sickeningly sweet honey aroma and then proceeds to swallow them whole. Once inside its stomach, the prey will succumb to a strong acid, which is capable of melting even the hardest material. Yes, that includes bones, and Victreebel has been known to eat a large animal or two. Heck, with its imposing height (5'07''), you could even fit a human in there.

11 Gengar

This list wouldn't be complete without a visit from the classic creeper himself. The original 151 contained a few visually unsettling Pokémon, but Gengar and his creepy smile are etched into the brains of all Pokémon fans. Gengar may not be as outwardly horrifying as some of the creatures on this list, but his Pokédex entries and wicked smile are enough to spook any would-be trainer.

Have you ever walked into a room and suddenly felt a cold chill rise up your spine? If so, you were most likely in the presence of a Gengar. These devious creatures, which stand at a fairly large 4-feet 11-inches, love to scare humans (and other Pokémon) by hiding in their shadows. The Pokédex entry in Pokémon Sun really ups Gengar's creepy factor by letting trainers know that if they do happen across this creepy creature to simply "give up" as there is no escape.

10 Yveltal

There aren't a lot of exceptionally scary Legendary Pokémon. This is most likely due to the fact that developers want their Legendaries to ooze badassery, rather than make people wet themselves. Still, there is on supreme creature that is pretty darn terrifying. Sure, Yveltal doesn't look like a nightmarish abomination. In fact, it looks downright cuddly with weird giant tail-arm-hand-thing.

Yveltal finds a spot on list because of its power and capability. The Dark-Flying type is nicknamed the Destruction Pokémon for rather concerning reason. When Yveltal reaches the end of its lifespan, it absorbs all of the life energy around it before balling up into a cocoon to sleep for 1000 years. This massive being is apocalyptic, self-preserving, and everlasting. The constant threat of sudden "absorption" is enough to put anyone on edge.

9 Cofagrigus

Earlier in this list we talked about Yamask and how horrible it is to realize that Pokémon Trainers are using and enslaving human souls. If you're smart, you'll stay far away from this depressed ghosts, because they might come back for revenge once they hit level 34. When a Yamask hits that magical milestone, it evolves into Cofagrigus, an eerie-looking Pokémon with a much more sinister ability.

You won't find a Cofagrigus staring at its mask in sadness, as it proudly displays it upon its coffin-like body. Four shadowy arms protrude from the ornate casket, waiting to grab anyone foolish enough to venture too close. Victims who end up in this Pokémon's grasp are stuffed into its body, drained of their life, and turned into mummies.

8 Mawile

Mawile should be classified as the Mullet Pokémon. It's all business in the front and party in the back. Except, in this instance, "business" is a deceivingly cute Pokémon and "party" is being torn to shreds by a series of sharp fangs. Mawile is pretty darn creepy. It's got an adorable little face and cute little arms, so long as you're standing in front of it. On the back of Mawile's little cranium lies a carnivorous maw, filled with tons of teeth and an insatiable appetite.

What makes this little Pokémon even creepier is that it's most likely modeled after a prominent Japanese myth called Futakishi-Ona. The fable centers around a seemingly normal woman that doesn't seem to eat much. It's later discovered that she has a horrifying mouth in the back of her head.

7 Jynx

I'm not sure we really need to explain why Jynx is on this list. This Psychic-Ice Pokémon has been unsettling trainers ever since her (Jynx are 100 percent female) introduction as part of the original 151. Past the fact that some think her appearance is racially insensitive, Jynx suffers from the fact that she simply looks creepy.

There are many Pokémon scattered throughout the universe that look human, but this dress-wearing damsel sports five fingers and a humanoid shape. Her face is rather eerie, sporting a blank stare and large lips that provide the bulk of her emotion. For the most part, Pokémon lore treats Jynx as if she's an innocent creature with an infectious dance routine. Still, being a Psychic Pokémon, she could inflict mental torture on her victims.

6 Porygon

Bear with me here because I know this pick will be met with scrutiny, but Porygon definitely belongs on this list. I know, there is nothing even slightly scary about geometrical shapes (unless you're bad at math) and Porygon looks like an adorable little low-poly dog. It earns its spot on this list is due to the completely real and extremely terrifying seizure epidemic that spread across Japan.

Over 700 children had a terrible fright when an episode (Electric Soldier Porygon) of the Pokémon anime sent them into a seizing fit. Apparently, flashing blue and red lights created a perfect storm for those susceptible to photosensitive seizures. Super fans will argue that it was Pikachu that actually caused these seizures, and although they may be technically right, everyone associates the event with Porygon's debut episode.

5 Guzzlord

Introduced as one of the Ultra Beasts in Pokémon Sun and Moon, this terrifying glutton is easily one of the scariest Pokémon ever designed. It's classified as the "Junkivore Pokémon," but it's obvious from its horrific appearance that it consumes more than just garbage. It's entire stomach is open, replaced by a massive maw with loads of razor sharp teeth. This is the stuff of nightmares, the crazed monsters we feared most when we were children.

Like many other Pokémon on this list, Guzzlord's Pokédex entry makes it seem even more menacing. Lore suggests that it eats constantly, devouring up entire buildings along the way. What's creepy is that none of its droppings have ever been found, suggesting its maw is an endless pit. If that isn't unsettling enough, you'll tremble when you realize that Guzzlord is 18-feet tall.

4 Mr. Mime

I'm sure quite a few of you expected to see this unsettling mime somewhere on this list. A collection of creepy Pokémon wouldn't be complete without an appearance from everyone's original Poké-nightmare. The first 151 Pokémon included a trio of spooky specters, some creepy crawlers, and whatever the heck Jynx was. Still, Mr. Mime takes the crown for the downright spookiest of the original set.

It's pretty easy to see why it's so unnerving. A lot of people are pretty phobic about clowns and Mr. Mime's got the make up caked face and silly hair down pat. It's a Psychic/Fairy type too, meaning its got all the skills necessary to completely melt your mind. All of this is made worse by the fact that it also belongs the "creepy Pokémon with five fingers club."

3 Froslass

At first glance, the "Snow Land Pokémon" looks like any other Ghost-type. It's got a mysterious masked face, ala Cubone, and a somewhat sinister glare. It's a special evoution, and only appears when a female Snorunt is exposed to a Dawn Stone. Special evolution conditions aren't exactly creepy but the legend behind Froslass (and it's behavior) are.

Like Mawile, this Pokémon is speculated to be based off a famous Japanese myth. Yuk-Onna is depicted as a vengeful spirit, often leading people into dangerous situations or freezing them solid with her icy powers. Froslass is one-hundred percent female and is classified as an Ice/Ghost Pokémon. It's safe to assume that developers drew inspiration from the scary Japanese legend when crafting this evolution.

There's also the matter of Froslass' Pokédex entry, which suggests that she freezes her prey to death and then displays them in her home.

2 Cacturne

Next, we have Cacturne, the stalker Pokémon. This creepy looking Cactaceae favors harsh desert environments and stays dormant during the day. That seems innocent enough, considering it's a cactus-based lifeform and the desert is disgustingly hot when the sun's up. Cacturne, however, stays dormant during the day for a rather peculiar reason. Night time presents the perfect opportunity to snatch up prey that's been weakened by the searing heat.

In Cacturne's case, prey also means humans. According to its Pokémon: Omega Ruby Pokédex entry, Cacturne travels around in a ragtag group, stalking travelers and biding their time until their victim is too tired to move. This sinister cactus is most likely modeled after the Babuk, a mysterious scarecrow-like creature. It is, after all, the "Scarecrow Pokémon."

1 Banette

This rest of this list wasn't really designed with an order in mind. That said, Banette was always a shoe in for the number one spot. When it comes to superbly spooky Pokémon, this bundle of terror and stitches takes the cake. Banette pairs two classically horrifying things together, ghosts and dolls. Buckle up, this creatures backstory is a wild ride.

Banette is born from pure hatred. It's a literal manifestation of emotion and rage. The "Marionette Pokémon" was once an inanimate doll, tossed away by its owner. Feelings of neglect and a need for vengeance brought this Pokémon to life. It lives in dark alleyways and garbage dumps, endlessly searching for the careless owner that threw it away.

To make things even creepier, Banette can use its body like a voodoo doll and will stick itself with pins and sharp objects to harm those around it. Its mouth is covered by a large zipper, which holds its energy firmly inside.