Biddy Ramsey was a holographic character in the Fair Haven holoprogram, set in 19th century Ireland.
Ramsey knew about faerie magic and how to fight it, gaining her knowledge from a book entitled Faerie Magick. Before she died, Ramsay gave Seamus the book, along with a spoon of hers, both of which he later used to hypnotize The Doctor. (VOY: "Spirit Folk")
This character was only mentioned in dialogue.