The ‘Woman of Secret Shadow’
Sauron’s vampire messenger, bat-winged and iron-clawed, who carried out his errands between Tol-in-Gaurhoth and Angband.
Little is known for sure about Thuringwethil, but all the indications are that she was a lesser Maia, probably one of the many brought into the service of Melkor during the early ages of the World. Though she is associated with Vampires, she is never explicitly said to be one (instead, she merely took on their form to carry her messages).
Whatever her origins, Thuringwethil’s fate is well established. Caught at Tol-in-Gaurhoth, her winged form was taken by the sorceress Lúthien, and in Thuringwethil’s shape she made her way with Beren to Angband. There they achieved the Quest of the Silmaril, and stole one of the Three Jewels from Morgoth’s Iron Crown.
Thuringwethil wasn’t the only one of Morgoth’s servants who could take on Vampire-form: Sauron used the same form to make a desperate escape from Huan the Hound of Valinor. Far later in history, Sauron once again used Winged Messengers to carry out his errands across Middle-earth: Nazgûl whose airborne steeds were perhaps inspired by Sauron’s Vampire servant of the First Age.
Notes
1. FA 468 is the approximate date of the destruction of Sauron’s Isle of Tol-in-Gaurhoth, in which Thuringwethil seems to have perished, or at least been robbed of her physical form.
2. There is no detailed information about Thuringwethil’s nature or origins, but it is stated that she was ’…wont to fly in vampire’s form to Angband’ (Quenta Silmarillion 19, Of Beren and Lúthien). If Thuringwethil could change her shape, as this suggests, then she was very likely a Maia, “dressing” herself with a different fána whenever executing her tasks as an Angband messenger.

