The Glashtyn (or Glashtin) is a mischievous, shape-shifting water horse from Manx folklore (Isle of Man), similar to the Scottish Kelpie, appearing as a horse with reversed hooves or transforming into a man to lure victims to watery deaths, but also known for hoarding treasure like pearls. It's a dangerous water spirit, often linked to shipwrecks, that can be controlled if its bridle is captured, revealing its connection to other Celtic water horses.

Characteristics & Forms
- Water Horse: Most commonly seen as a horse, often with reversed hooves or sticky hide to trap riders.
- Humanoid: Can take the form of a handsome man to seduce, or sometimes a hairy man or old woman.
- Treasure Hoarder: Has a fondness for pearls, stealing them from shipwrecks and victims.
- Manx Name: Also called Cabbyl Ushtey (Water Horse) or Tarroo-ushtey (Bull-horse).
Behaviour & Legends
- Lures Victims: Like the Kelpie, it tries to get people to ride it into lochs or rivers to drown them.
- Strength: Possesses immense strength, capable of carrying multiple people at once.
- Control: Can be controlled if someone gets hold of its bridle, especially one marked with a crucifix, binding it to service.
Connection to Kelpies
- The Glashtyn is part of a broader tradition of Celtic water spirits (like the Scottish Kelpie or Irish Each-Uisge), sharing the shape-shifting water horse theme but with unique Manx characteristics, particularly its association with treasure.