Emma Gilbert is one of the main characters who became a mermaid in the Australian television series, H2O: Just Add Water. Along with Cleo and Rikki, Emma discovered her powers after her trip to Mako Island.
Cast characters from other franchises as the Disney Princesses (and some other heroines who aren't "officially" part of the lineup.) No male characters or Disney characters, please. (Marvel and Star Wars are fine!)
