Kelpie of Loch Ness

The Kelpie of Loch Ness is a legendary creature from Scottish mythology and one of the more recurring folk tales that seek to explain the infamous Loch Ness Monster itself - the story was told long before the Loch Ness Monster as we know it today was envisoned and while recent lore prefers to see the Loch Ness Monster as a dinosaur or sea-dragon the folk tale of the Kelpie remains popular in some sectors of Scottish society and the tourist trade.

History
In the early 19th century it was said that a particularly powerful and wicked kelpie took to haunting the forests near Loch Ness and had its own saddle and bridle, which had great magical powers and also kept the demon alive - without these two items the spirit would die in less than twenty four hours.

After many years of terrorizing the area, drowning and killing people as its kind were prone to do, a Highlander by the name of James MacGrigor decided to rid the world of the monster and managed to catch the beast by surprise and cut off its saddle and bridle.

Quickly realizing it would die the kelpie begged MacGrigor to give back its items but he refused, the demon pursued him to his home and gloated that he could not bring the demon's saddle or bridle into his home as the man had a cross over his door : the man outsmarted the demon by tossing the items in through the window instead.

Now with no means to retrieve its items or exact revenge on MacGrigor the kelpie fled into the forest, cursing and swearing as it awaited its inevitable death.

the kelpie's saddle and bridle were said to be passed down by MacGrigor to others and held great magical powers, though in an ironic twist the once demonic items seemed to gain holy properties of healing - likely due to MacGrigor's own faith (as with many such tales it also likely tried to symbolize Christianity's conquest over the pagan world).