The world has no shortage of scary creatures, dozens of different cultures building together a large book of demonic like creatures, doesn't matter which culture each one has something scary under its belt.
#10, Werewolf: This is a common one, something I have put on a few lists but it is for good reason. A person can become a werewolf through being bitten by one, being cursed or by doing a special ritual but it will always end in blood. Only a select few of individuals can keep their minds intact when transforming others will become feral, attacking friend and foe alike. Upon transforming it will gain great amounts of strength and speed as well as sharp claws and teeth, the only way to take down a werewolf is with a silver bullet. If you ever face one without silver it might be all over for you.
#9, Skin-Walker: In Navajo legends there is a being called the Skin-Walker, depicted as somewhat of an opposite of medicine folk or healers Skin-Walkers are said to be witches. Beings who can take form of animals or posses human bodies. The Skin-Walker can be male or woman but is generally a male. Many stories have mixed endings with sometimes the possessed person killing the Skin-Walker or the other way around, sometimes even a stalemate can occur or the creature being scared off. Not a whole lot is known about these beings from legend since many Navajo folk don't wish to speak to outsiders about them.
#8, Dullahan: The Dullahan is a Headless Horsemen character from Irish Legends, it takes on the role of a Grim Reaper and a Banshee. The Dullahan travels around searching for its victim, it holds a sinister smiling head in one arm and a supposed spine in the other which it uses as a whip. The Dullahan is said to be unstoppable, it cannot be locked out nor be beaten with conventional weapons. If the Dullahan spots you while it is working it will shower you with blood effectively making you its next target. If it speaks your name you are dead, if you see it working you are dead, basically the Dullahan is just death.
#7, Jikininki: Hailing from Japan Land the Jikininki is a man-eating ghost, the tale goes that if a man is truly greedy when alive he will turn into one of these ghouls. Don't really know how that's a punishment. The Jikinink is said to look like a decaying corpse with very sharp claws and glowing eyes. It is a little unknown if the creature is similar to a zombie or other flesh like eating humanoid being but who knows.
#6, Hell-hound: The name kinda says it all, it is a hound, from Hell. The Hell-hound is supposedly much larger then an average dog, maybe getting close to the size of a horse with great strength and speed. The appearance can differ but generally it is a large black dog with glowing red eyes, sometime it is engulfed in fire. Cerberus from Greek Mythology is supposedly a three headed Hell-hound. In any case it is a very dangerous creature, not fond of anything and always hungry. Might want a muzzle for this pooch.
#5, Mr. Hyde: Edward Hyde is the evil counterpart of Henry Jekyll, Jekyll after creating a potion to separate his good personality from his evil one. Unfortunately as the story goes on he becomes addicted to the potion and the murderous Hyde eventually comes out more and more. Hyde is murderous, cold and has no value for human life other then to watch it slowly disappear from a persons eyes. He even went as far as to beat a man to death with a cane. While his appearance may not be terrifying its the possibility then anyone, even the most mild mannered of fellows could have a very dark history underneath. That anyone can go from a kind and normal person to a blood hungry psychopath.
#4, The Pale Man: In the Movie he is a humanoid like creature with loose skin and eye balls in the palms of its hands. It has an appetite for little children and despite it looking quite weak it has a penchant to tear limbs off. Though not much of it was shown off in the movie it was a terrifying creature, chasing after Pan and trapping her before she managed to escape. Many stories are told of creatures devouring little children but seeing one actually getting very close to it wa scary.
#3, TikTik: The TikTik is a shapeshifter with as common knowledge with many monsters, they like human flesh. These creatures can shapeshift with their main form being a giant bird. When out in the woods if you hear a TikTik be careful, the louder the sound is the farther away it is, so if its quiet you best be prepared. Though their is some varieties of the creature they have some common traits such as loving children and fetuses. When as a human they are shy, elusive and keep to themselves. Beware of the anti-social folks!
#2, Baba-Yaga: Yaga is depicted as an old woman who flies around in a mortal wielding a pestle, she lives in a house resting on two large chicken legs in the middle of the forest. She is said to help or hinder those who come across her though it is usually the latter. Russian folklore has her made as a rather big icon appearing in several movies, she can be very dangerous despite her looks, she may not be a demon or a powerful god but it would be wise to avoid this old lady.
#1,Lucifer: Just for the sake of it I will put this classic bad guy down, though some stories or believers might say he is not as evil as he is depicted we shall do the evil version anyway. The Devil is the main villain, the head honcho of evil. Usually possessing armies from Hell, powerful magic and a silver tongue capable of coercing even the most strong willed people into doing things they normally wouldn't. In a constant battle against God he is what every dude with evil in his heart aims to be, for when you are the Devil, few can stand up against you.