Mermaids are female half-human, half-fish creatures who live in St. Elle's Seabed, the Sea Kingdom of Avalar. The males are called mermen, and those exceptionally skilled in Water Magic are called Undines. They first appear in Wiccan of the Sea.
Notable merpeople[]
King Neptune: the king of all merpeople and husband of Queen Tethys. He is often strict when it comes to his kingdom laws, but is a very nice monarch nonetheless. He cares very much for his daughter, Princess Marina. Neptune is a blue whale merman.
Queen Tethys: the queen of the merpeople and wife to King Neptune. She is more lenient than her husband, but a very capable ruler at any rate, especially the laws about human coexistence with merpeople. Tethys is a great smelt mermaid.
Princess Marina: the daughter of Neptune and Tethys, and the younger sister of Prince Caspian, Prince Reef and Prince Sargasso. She is the Melancholic of the four's temperament ensemble, but really wants to explore the world above St. Elle's Seabed. Marina is a blue tang mermaid.
Prince Caspian: the eldest child of Neptune and Tethys. Of the four royal children, he is the Choleric member due to his snarky attitude and general toughness. He takes his future kingdom very seriously, though does lighten up in some times of peace. Caspian is a yellow tang merman.
Prince Reef: the middle brother of the three princes, and the one who is Phlegmatic in the temperament ensemble. He is a kind and caring prince, but his flaws can dip if he ignores them. He is also the biggest eater of the four children. Reef is an ascension wrasse merman.
Prince Sargasso: the youngest prince and the penultimate child of Neptune and Tethys. Due to his fun-loving attitude and carefree personality, he is the Sanguine member of the temperaments. While he can neglect his prince duties in favor of contests and water sports, he is a capable prince nonetheless. Sargasso is a clownfish merman, fitting his fun-loving personality.
Dorsola Finn: the main antagonist of the St. Elle's Seabed story arc. She is a beautiful mermaid, always winning beauty pageants and in general the prettiest mermaid there is, but she hides a dark secret: she can command the Forbidden Arts like most villains in the series. She eventually met her demise at the hands of Carl Cooper and Marina. Dorsola is a royal gramma mermaid.