Demons from the Ancient World

Originally Posted by MatthewM

Vampires? Do you know where it mentions that? I'm not doubting you, I'm just curious. I remember something was mentioned once with a vampire and werewolf but I can't recall where I read that...

You might be thinking of the Silmarrillion when Luthien and Beren transform into a vampire and werewolf respectively. Other than that I can't think of a mention in LOTR.