Madame U
Madam U (Vadona Winifred Euryale) is a Gorgon and the owner of the Prestor John's shop in the Liverpool Avalon. Madam U is blind, ensuring the safety of her customers from the petrification that she would otherwise have. How she came to be blind is unknown. She has limited vision though her snake heads. She admits they are not as good as her original eyes, but are enough to get by. The snake heads also have a sense of smell/taste. (mentioned in comic here) Her hair-snakes are of the garter snake variety, meaning that they are not venemous.
Madam U is very old, and as such has a large amount of knowledge about mythology and its related subjects, so she is the first person to be consulted by Blanche and Anthony when Anthony turns.
Madam U is partially responsible for Tony's current condition, as the first medallion she offered him seems to have broken a spell keeping him human, although she had no way of knowing this would happen.