There is a creature, a Fay nightmare long forgotten by us regular folk, who only comes out at night and haunts the dirty streets of Dublin in the wee hours. No one has said his name in 300 years and no one has believed in him since the industrial revolution.
But he is still very much alive.
He sneaks down cobblestone alleys only venturing into the rural areas when desperate. He skulks in the shadows and appears to bend and shrink into the corners moving slowly, his every step deliberate. He can only ever be seen from the corner of your eye, disappearing when you look straight at him in a trick of light and magic that has allowed him to survive. He feasts on garbage, rotted food, and the occasional hapless drunk.
Hidden from view by a magic older than the written language the only sign that he is nearby is the smell of carrion as it drifts up on an evening breeze. Though you cannot see him your body can sense the danger causing your skin to prickle, your hairs to stand up in warning, and your feet to pick up pace.
This is how he chooses his victims. The more imagination you have the more likely you are to be caught for only when you believe in him can he be truly seen, his greatest survival mechanism becomes your worst nightmare.
His muscles bulge unnaturally and his skin is all sinew and rough leather. His bones protrude at odd angles, the elbows always curved and his neck bent forward at a disturbing angle. He is grizzled and worn with a stooped back but nothing about him looks weak. He radiates a terrifying strength despite his odd and haggard appearance.
If you are ever unlucky enough to truly see him he at first appears short, stooped in the corner by a trash can all sharp angles and low to the ground, but when he stands up tall cracking his bones and stretching he is nearly 6 feet.
He smiles when caught, his two rows of teeth gleaming in the light of a nearby streetlamp. They are stained the rust of blood red and half rotted but still sharp.
There is hatred in his hungry eyes, a deep loathing for mankind that instantly petrifies anyone who makes eye contact, forcing even the strongest man to become a deer caught in the headlights of a superior predator. Once powerful and now reduced to eating scraps he relishes any instance where he can eat a common man, silencing his victims by slicing out their tongues with his long fingernails and slowly picking their bones clean, sucking the marrow while his prey still lives and writhes in pain.
He may be long forgotten but he does not forget.
Instead he bides his time.
He will become known again.