Yellow Vampire dragons were mentioned once in How to Speak Dragonese:
- "An enormous number and variety of dragon species were being held prisoner behind the bars of this cage. Deadly Nadders, Flying 'Gators, Big Spotted Gormlesses, Yellow Vampires, Common or Gardens—you name it, they were all there, trapped together in a furious tangle of talons and wings and fangs, ready to be sent back to the restaurants and shoemakers in Rome."
- ―How to Speak Dragonese
This is what Hiccup saw after being captured by a Roman ship. Yellow Vampires are not mentioned again, nor is any description given. One theory is that Yellow vampires are a variety of the Vampire Dragon, which are typically dark in color.
- How to Speak Dragonese (Book 3), Cressida Cowell. 2005