The goblins are probably the fairies best known to the common folk. They are mischievous parasites, stealing everything they need and causing misfortune by making pranks on the lowly humans. They usually live close to villages and farms. Goblins rarely kill humans, since they are their biggest source of food and entertainment. Sometimes, a goblin family can live next to a farm unnoticed for a long time, their actions being attributed to animals, failing crops and bad luck.
Ogres & trolls:
Ogres are big, hulking brutes populating forests and hills, and are rarely encountered in civilized areas. They roam the countryside hunting for game, and can eat enormous amounts of meat in a day. They do eat humanoids when given the chance, and when they encounter travelers they enjoy toying with them before attacking. Ogres are very competitive, and potential prey can escape by staking their life on a game.
The trolls are territorial creatures, and often make their homes in caves and rivers. They loathe letting anyone into their territory, but are cowardly creatures and will not attack anything they think can defeat them. If the troll encounters anyone smaller than itself near its home, it will try to bully the intruder to leave, and attack when threats fail. On the rare occasion it meets something as big as itself, it will hide or flee.
Both trolls and ogres are as stupid as they are big, and the easiest way to survive an encounter is to use wits. Clever travelers have been known to trick ogres and trolls into fleeing in fear, disemboweling themselves and waiting to attack until a worthy opponent arrives (Don't eat me, i'm way too small to fill your belly. My brother'll be by soon, and hes real big!).
The fey are beautiful and carefree fairies that rarely leave the woodlands. They enjoy feasting, dancing and making love, and almost never do anything of use to themselves or others. Fey enjoy making pranks on travelers who enter their woods, and what they consider good fun can often turn out deadly for the victim.
Grigs resemble a cross between elves and crickets, and like to steal from travelers. They choose what to steal almost arbitrarily, and often discard the loot after playing with it for a short time. This can still be annoying to the victim, and many people who run across a grig have had the misfortune of walking home through the woods without shoes or sleeping in the cold because it stole their flint and steel.
Pixies often follow travelers for long periods of time, sabotaging their efforts to survive. Someone pestered by a pixie might find worms in their rations, having their firewood covered in water when they turn their back or drawing their bow to find the string has been cut.
Dryads are fairies closely linked to the trees, and like to make travelers lose their way. By planting false clues and changing the terrain they can lead a victim in circles for days, until it is completely lost and can only rely on luck to make it home. Most starve to death long before they can find their way out of the woods.
Nymphs and nixies are comely fairies who like to tempt male travelers. They allow the victim short glimpses to pique their interest and lead them away from the road and deep into the forest. Nixies trick their victims into marshes or ponds, and let them drown. Nymphs more often kidnap their prey, and keep them as slaves and pets for their own amusement. They usually strangle the victim when they grow bored of it, but a slave who manages to keep a nymph happy for as long as a year is granted freedom, and sometimes a boon if the slave has proven exceptionally entertaining.