Kelpie

The Kelpie (variations are known as the each-uisge/aughisky or water horse) is a supernatural creature from Celtic Folklore. It is believed to haunt the rivers and lakes of Scotland and Ireland. It is usually black, although it can be white as well. It appears as a horse or pony, although its mane is always dripping water or tangled with seaweed. They are also known to transform into beautiful woman to lure young men into traps, usually into water so it can eat them. A Kelpie has the strength of 10 regular horses, but they hate to be enslaved. It is wise to stay away from them.

Strengths
Kelpies have been known to disguise themselves as black mustangs near a loch and lure men, women and children onto their backs for a seemingly innocent ride. But then the kelpie crashes headfirst into the loch, dragging the person to their watery grave. They also, as previously stated, disguise themselves as humans. Their ability to change forms may have something to do with a silver bridle. In one particular tale, a lady was able to change a kelpie into their equestrian form by removing the bridle, and back to their human form by putting the bridle back on.

Appearance
Horse Form: In their horse form, Kelpies disguise themselves as black mustangs. In other versions, they are said to be horses with snakes for hair.

Human Form: They are known to be handsome in their human form.