Rosanna Calvierri

Rosanna Calvierri was the alias used by the matriarch of a group of Saturnynians that were fleeing from a crack in time.

Biography
Rosanna and her children fled to Venice where she and her eldest son, Francesco, used Perception filters to appear human. They had come to the Italian city because of their marine nature, and to exploit the fear of the plague. The race set up a "school" under her headship, which gained notoriety in the city as a plague-free haven, and so it was an attractive proposition for fathers to bring their daughters to the school.

Once the girls were in the schools, their blood would be replaced with that of the Saturnyians, and they would be transformed into females of the species, ready to help drown Venice and form a new race with the other male survivors. Fortunately, the Doctor disabled her machinery leaving her plans in tatters. With no hope of rebuilding her species and her perception filter broken, Rosanna was stuck in human form. She threw herself into the canal and was devoured by her children because, although she was their mother, they thought she was a meal. (DW: The Vampires of Venice)

Behind the scenes

 * Rosanna's school is most likely a reference to "the blood countess" Elizabeth Báthory who used the same trick to feed her blood lust.