Ariel is a kind mermaid, who falls in love with a human prince named Eric. She eventually gains a magic bracelet which allows her to switch between mermaid and human form whenever she chooses, allowing her to be with her prince.
Ursula was a mermaid, and the daughter of Poseidon, who used Ursula's voice to lure pirates to their deaths. Ursula decided that she wanted to use her singing voice to make people happy, instead of using it as a weapon. She meets Captain Hook, although Poseidon angers Hook which causes the pirate to steal Ursula's singing voice with a magic seashell. Angry with both Hook and Poseidon, Ursula uses Poseidon's trident to transform her tail into tentacles and becomes the Sea Witch. However, after Hook restores Ursula's singing voice and she reunites with her father, all is eventually forgiven and Ursula returns to the sea.
- S3, E01: "The Heart of the Truest Believer"
- S3, E06: "Ariel"
- S3, E07: "Dark Hollow"
- S3, E10: "The New Neverland"
- S3, E17: "The Jolly Roger"
- S4, E11: "Heroes And Villains"
- S4, E12: "Darkness On The Edge Of Town"
- S4, E13: "Unforgiven"
- S4, E14: "Enter The Dragon"
- S4, E15: "Poor Unfortunate Soul"
- S4, E16: "Best Laid Plans" (flashback)
- S6, E15: "A Wondrous Place"