This is the Kelpie. I created this cryptid creature / monster art for Fairytales and Myths.
Kelpies, Each-Uisge, and Water Horses are Celtic legends about shape-shifting water horses that lure victims to their doom.
With this art piece, I was trying to capture the majesty of the moment used by the creature to entice unwitting women to their doom. Thus far, my favorite rendition of the Kelpies is in the anime Delicious In Dungeon where the dwarf is fooled and almost drowned.
Check out the Kelpie page for more details.