Daughter of the mighty sorcerer Ferumbras and granddaughter of Fermuba. Not much is known about this woman.

Her kidnapping by Nightmare Knights is possibly what triggered Ferumbras' first attack on Thais. Fortinbrae was then being hidden in Carlin. During Ferumbras' second attack, they had to kill her and retrieve something from her corpse before they were able to finally defeat him.

Occasionally, during Test Servers, Cipsoft member used to log onto character called Mistress Fortinbrae to attack other players in Thais and Carlin, similarly to how Ferumbras did it in the old days of Tibia. The character was a Sorcerer and had special abilities like unusually high base speed, very strong self-healing and ability to summon Demons, Hellhounds, Hellspawns, Nightmares, Zombies and Essence of Darkness.