Ursula

Ursula is one of the main antagonists of Season 5 and a minor antagonist/anti-hero in Season 6. She returns as a hero in the series finale.

Throughout Curse of the Lycans
Ursula is born a mermaid in the waters of Agrabah. Abused by her father and fed up with her life as a mermaid, Ursula longs to be human.

One day Ursula meets a woman as she sails the ocean. The two form a close bond and the woman even decides to adopt Ursula if she becomes human which with the help of Tinkerbell she does. Unfortunately for Ursula, the woman made a deal with a mami wata to become pregnant if she were to turn her back on Ursula. Upset, Ursula uses her father's dark magic to transform herself into a cecaelia.