Caboose
Gragnfeld: A man cursed with changing into a bloodthirsty beast that can only be counteracted by love. The Gragnfeld has a large torso covered in fur like a bear and smaller but muscular hind legs, the arms are long and muscular. Its head is large and rounded and it has horns like a Scimitar Oryx. If the Gragnfeld has horns 7 inches long it's too late and it must be slain. It does not return to human form but it regains its old mind if it does beat the curse. (That almost never happens) Weakness: cut its horns, its ribs are the weakest bones in its body but they're hard to reach since the beast is hunched exposing its back more,
Dragons: There are only 8 Dragons in the world, most are dormant or in faraway places. Only 8 can exist at a time, they asexually reproduce.
Giants: Giants roam the land in small packs, they prefer secluded areas away from humans. If they attack or join in battles they use giant scythes built for mowing fields, but they cut through people just as well. Or they have giant blades attached to their feet they use to slice people up. They only use clubs or hammers when fighting other giants. Archers should aim for their eyes and the testicles, artillery should also be used against them. They hate Hive gas which is a collection of spores that sting intensely, they breathe that stuff in and it attacks the throat and lungs. (range= 13-18ft)
Golem: A creature made from the bonding of soul and stone, it is a cruel punishment and Golem's are made to be servants if their master dies they are left to roam and sometimes rampage. Golem's are mostly impenetrable to flame and steel, but they are of magical means, things that negate magic are recommended.
Ghouls: Long, pale, vile is what the Slayer referred to Ghouls as, they are humans by day, by night they grow into towering, limber beasts with white skin. They feast of corpses of all they can find. Just becuase you are not dead does not mean they won't make a meal out of you. They kill their prey and wait for rot to set in before feasting. Come winter they hide the bodies in pits or tunnels they construct until the last snowfalls. They hate bright lights, flame near their eyes alone could blind them.
Trolls: Trolls are large, disgusting and hunched over creatures that reside in the mountains, caves or under bridges. they have large lower jaws used for crunching rock for them to eat. They also enjoy raw meat from almost anything living or dead. Their skin is thick and tough, proving to be resistant to blades and fire. Drawing the creatures out into sunlight petrifies it. Poisoning it's food is easier than it sounds.
Werewolves: Pure blooded werewolves can turn whenever they want, those turned into werewolves through curses, or purebloods become ferals and only change on the full moon and prove to be larger and more monstrous. Silver works a charm. Wait after a full moon if you can.
Vampires: (Some ideas nothing beyond stereotypical vampires so far.)
Mananggals: Female vampiric creatures that detach themselves from the lower halves of their body and spawn bat wings from their back. They have large fangs and long straw-like tongues to devour vital organs, they often target pregnant women for their foetus'. Finding and destroying the lower half of the body means the creature can't return to human form and will slowly die, sunlight will slowly kill the creature.
Chupacabra: A vampiric canine that creates the wound and uses its long tongue like a straw to drain the blood and bone marrow. A good method is to leave some dead cattle in the area and fill that with poison.
Razormouth Spiders: Giant spiders that have no fangs instead they have a round mouth filled with rows of razor-sharp teeth, it swallows it's prey whole and shreds them into the stomach. Their front legs have large rounded stumps they use for jabbing or crushing. Their underside is filled with quills that are poisonous and can be launched. The poison paralyzes its victim. Light it on fire, the quills are flammable, make it swallow something sharp Godfried the Slayer once threw his sword down a Razormouths throat and it died in a matter of seconds. Cutting its legs off is always a good place to start.
Jorogumo: When a spider turns 400, it becomes giant and the op half becomes that of a gorgeous woman to lure men. You can tell its not real due to the smell, sniff for honey or search for legs, Jorogumo doesn't have human legs, use fire, attack the human head.
Kamaitachi: A large white weasel that glides through the wind with sickle-like claws hanging from its front paws that it uses to slash people. Attach a blade to a rope and swing that around, or fire.
Mare: A demon that sits on top of peoples chests and fills their mind with night terrors that can drive someone to insanity or intense sleep paralysis that lasts hours.
Draugr: Frozen undead warriors that don't leave their bodies if they die before their quest is fulfilled. Instead of returning to their quest they attack humans. Fire, attack their eyes they die slowly without them.
Wraiths: Knights that are killed unjustly or die under dishonourable circumstances, after death, they receive a choice to return as a Wraith to haunt those who killed them. Most don't because after they've dealt with their own problems death keeps their soul. Wraith's currently haunting are black shadows of their former selves clad in armour. Wondering Wraiths float. Draw a circle of salt, even throw salt at it, fire won't work. If you want to hit it make saltwater and wash your blade with it.
Banshee: A female ghost that wails, warning of a horrible death.
Dire Bears: A giant bear that stands 11ft tall
Dire Wolves: A large species of wolves
Griffins: Majestic monsters that are best left alone.
Fallow Trees: Carnivorous trees that latch onto their prey with vines and branches and drag them to the trunk to devour them.
The Lich: A monster residing in the Haunted Forest, suspected for creating the forest. Its head is a stag skull, it has giant crows wings, it's arms are made of branches, it's body and legs is that of a man.
If I haven't put descriptions on a monster I'm still conceptualising it.