Gabriella Xavier was the last Queen of Camelot, and the daughter of King Xavier. When she was young, she fled Camelot with her grandmother during an assassination attempt that left her mother dead. They were both unknowingly saved by Salazar Slytherin and the other Hogwarts founders from an attack by a werewolf. When she was 18, she would marry Derrick, and bear a son, the Little Prince.(Later James). She was also the distant ancestor of Harry Potter and his children.
- Gabriella made an appearance in James Potter and the Morrigan Web through the Mirror of Erised. She also appeared in the short story "Merlin's Gift.", although she wasn't identified by her name.
- Interestingly, her son shares the same name as a later descendent, James Sirius Potter. Gabriella even admitted her delight with the name James in the Mirror of Erised.