Melusine was a French witch who lived in, and previous to, the 1920s. She worked at the French Ministry of Magic in the Records Room Archives.
She can control Matagots who guard the archives from intruders
Melusine or Melusina is a figure of European folklore and mythology whose legends are best known in Northern France, Luxembourg and the Low Countries. She is a female spirit of fresh water dwelling in a sacred spring or river and as such is often depicted as mermaid-like but also with wings and two tails.