Nettles, the fire witch of the vale.
High in the mountains, the unthinkable happened one night as Ser Robert and his men huddled about their campfires. In the slopes above, a cave mouth was visible from the road, and a dozen men climbed up to see if it might offer them shelter from the wind. The bones scattered about the mouth of the cave might have given them pause, yet they pressed on ... and roused a dragon. Sixteen men perished in the fight that followed, and threescore more suffered burns before the angry brown wyrm took wing and fled deeper into the mountains with "a ragged woman clinging to its back." That was the last known sighting of Sheepstealer and his rider, Nettles, recorded in the annals of Westeros... though the wildlings of the mountains still tell tales of a "fire witch" who once dwelled in a hidden vale far from any road or village. One of the most savage of the mountain clan came to worship her, the storytellers say; youths would prove their courage by bringing gifts to her, and were only accounted men when they returned with burns to show that they had faced the dragon woman in her lair.
— Fire and Blood