The Morrígan
The Morrígan emerges from this cave in the Táin Bó Regamna on a chariot pulled by a one-legged chestnut horse. She brings a cow, guided by a giant with a forked staff, to breed with the Brown Bull. In another story the Morrígan takes the cows of a woman named Odras who follows her into the cave before falling under an enchanted sleep, upon awakening she sees the Morrígan who whispers a spell over her, turning Odras into a river.