Meet Percy Jackson

Shapeshifters who can move between seal and human form by shedding their seal skin. They often have a rather choppy relationship with hu-manatee.

Find them: around the northern islands of Scotland. Try Orkney, where legend has it that a young woman had a baby boy by a selkie who lived on the island of Sule Skerry. The father arrived at the birth, placed a gold chain around the boy’s neck and took his son to live with him in the waters. However, before he left he predicted that the woman would marry a whaler who would one day kill both him and his son. The woman did indeed go on to marry a gunner, who one day returned from a hunting trip with a gold chain found around a seal’s neck, much to his wife’s devastation.

Looks that can kill, literally. Those who have the misfortune of seeing the yellow eyes, teeth and hair of the Welsh Fad Felen ('Yellow Plague') will soon encounter death.

Find it: The most famous tale hails from Llanrhos church, where Maelgwn Gwynedd, King of North Wales, died after reportedly seeing the Fad Felen through a keyhole. Spookier still, Maelgwn Gwynedd’s death was prophesied by Taliesin the poet. “A strange creature will come from the marsh of Rhianedd,” he said, “to punish the crimes of Maelgwn Gwynedd; its hair, its teeth, and its eyes are yellow, and this will destroy Maelgwn Gwynedd”.

The Scottish-English bluecaps and the Cornish-Welsh knockers are mining spirits that make knocking sounds to warn miners of impending collapse. What a rocking coal-ition.

Find them: Pretty much any mining landscape across England and Wales - although Cornwall has some of the most impressive knockers in the country (okay, we’re done with the knock-knock jokes now). Take a stroll around the region of Ransom mine, where a father and son duo reputedly met a sticky end after trying to cheat the magical mini-miners.

Devours anyone who enters its waters. This demonic lake monster has been described as a crocodile, a beaver and a dwarf-like creature - whichever floats your boat.

Find it: Where better to track down the Afanc than at the lake that bears its name? Llyn yr Afanc in the River Conwy is the original home of this many-toothed mythical beastie. Legend has it that the Afanc’s demonic thrashings once drowned all but two people in Britain… so clearly Brits hail from a rather narrow gene pool.

A lone wolf who leaves fish on the windowsills of the poor and old of Shetland. A sort of canine Robin Hood minus his merry mutts...

Find it: on the Isle of Unst, where the Wulver lives alone in a secluded cave - although the exact location of his underground home is shrouded in mystery. Maybe that’s why they call him a where wolf.

These murderous creatures have blood on their heads as well as their hands - they dye their caps with human blood! But if you brandish a cross, they go up in flames, leaving only an old tooth behind. To be displayed as a victory plaque perhaps?

Find them: all around the Scottish-English border. Perhaps the most atmospheric spot with redcap associations is Hermitage Castle in Roxburghshire, where evil 14th-century familiar Robin Redcap wreaked havoc under the aegis of his master William de Soulis. Some legends say that he remains at the castle guarding a horde of underground treasure…

These flaming fish demons have eyes all over their head - no chance they won’t sea you. When storms rage, they can be heard ferociously singing for joy as they lurk under the swirling waters. If a ship capsizes, you can be sure they’ll gobble up the hull thing.

Find it: off the shores of Shetland, which seems to have more than its fair share of supernatural sea monsters. Shetland’s sailors also have the boat-munching Bregdi to contend with - a tentacled terror, which can only be deterred by cold steel… or a strategically-thrown amber bead.