I can probably provide a useable list of types to get started...
Let's see:
Wmach: These are primordial Welsh giants who are able to transform themselves into giant stone "menhir" or standing-stones, at will.
Gruagach: The Scottish equivalent of the brownie, a small, gnomish being with the ability to transform itself into a large white dog.
Bradan Feasa: The "Salmon of Wisdom": An enormous, ancient/immortal, very intelligent salmon with the gift of speech.
Leipreachan: Another spelling for the more popular "leprechaun", these are often depicted as little old men, but my research says that they can be human sized fighters, with the ability to age themselves, or revert back into children. They have the power of illusion, and guard the treasures of the Fae.
Bean Nighe: A fae washerwoman who washes the graveclothes of those about to die. A specific type of Bean Sidhe (or "banshee"), she dresses in green, and has webbed feet. Like the leiprechaun, she can also appear as either a beautiful young woman, or a crone, at will.
Spriggan: Fae bodyguards, although they usually appear as tiny, hideously ugly green men, they have the ability to swell in size at will, becoming huge. They armed themselves with clubs studded with poisoned thorns, and often stole babies.
Meri-Morgan: Beautiful water faeries who ride seahorses, and play the harp. Despite their peaceful appearance and ways, when in danger, they have the ability to call upon their kin-the beautiful but vicious Merrows--wild nymphs of the sea
Dullahan: A headless horserider armed with a whip made from a human spine. Ignores gates and locks. Fears gold.
Kelpie: Black (sometimes white), extremely strong-10 times the strength of a normal horse-amphibious Fae horse that drags children into the water to drown and eat them.
Seonaidh: An ancient fae sea spirit that grants blessings. Resembles
an old woman with long, wet white hair, with a fish's tail and hands like squids.
Cyhyraeth: A disembodied fae spirit that governs the moment of death.
Coblynau: Gnomelike Welsh beings that haunt mines. Only a foot and a half tall, and very ugly, they work constantly, but never finish their work, and can cause rockslides.
Gwrach y Rhibyn: A winged black hag with black teeth that forebodes death. She can take the form of a lizard, and in that form eats babies. She can also turn into mist.
Clurichaun: Drunk and surly cousins of leiprechauns. They ride sheep and dogs, and are perpetually drunk. They haunt winecellars, guarding them from thieves, unless treated badly.
Fachen: A creature with half a body, split down the middle of it's torso, from top to bottom. It has a whole head, but it's head is terrifying, covered in jetblack feathers, and with a huge mouth. Enormously strong, in it's one arm the Fachen wields a magical chain that's capable of cutting through tree limbs. It can destroy an entire orchard in a single night with it's chain.
Boobrie: A giant predatory fae bird that haunts lakes and natural sources of salt. Resembles a giant loon, but with white markings, and the ability to roar.
Tylwyth Teg: Golden-haired faeries of Wales. Neither entirely good or evil, but do kidnap children. Afraid of iron.
Jili Ffrwtan: Proud, and amorous, female members of the Tylwyth Teg. A bit like Rumplestiltskin, in that Jili Ffrwtan would take on work that other woman couldn't do, but would demand the woman say her name in 3 days' time, or forfeit everything they owned, including their husbands and children.
Ghillie Dubh: Wild, but shy fae who guard trees. Covered in dark hair, they clothe themselves in moss and leaves. They're most active at night.
The Cailleach: One of the most powerful of all the Fae, the Cailleach is the queen of winter. A gigantic old woman who carries a mallot with which she shapes the hills and valleys of the land, she turns to stone with the coming spring, turning back when autumn arrives.
Afanc: An enormous and hideous fae water demon.
Each Uisge: A similar creature to the kelpie.
Crom Cruach: "bent blood ", a powerful and ancient fae.
Crom Dubh: "bent black", another powerful and ancient fae.