- Name: Melody Athena Thatch
- Age: 14
- Hair: Black
- Eyes: Blue
- Likes: The sea and ocean, swimming, exploring, treasure hunting, Sebastian, Tip, Dash, Dax, Flounder, her family, singing, adventure, making new friends and companions, learning more about her mother's otherworldly heritage and her father's legacy and adventures.
- Dislikes: Rules, reprimands, secrets, her mother lying to her, her mother forbidding her to go to the sea
- Family: Eric Thatch (father), Ariel (mother), King Triton (grandfather)
Melody is sassy but well-mannered, and has respect for her mother Ariel, her father Eric, and others. Melody's curious and tomboyish nature leads her to collect all sorts of items from the sea, a parallel to her mother at age sixteen only in reverse. Melody's swimming proficiency and ability to hold her breath for long periods comes from her merfolk parentage. Largely because of her being half-mermaid, she was also seen as somewhat of an outcast, as evidenced by the guests at her fourteenth birthday celebration shunning her. She is also shy around boys, becoming quite flustered when a merboy she found attractive tried befriending her in Atlantica. She later met him again after the wall was disintegrated, with both recognizing each other. Despite being tomboyish, she has a girlish styled bedroom.
- SeaBlade Wielder: She wields the Seablade after it was passed onto her by her father.
- Merfolk Heritage: Due to being half-mermaid, Melody is able to switch between being a mermaid and human although this transformation process is only used for emergencies due to it being exhausting for her.
- WaterBending: Also like her mother, Melody uses hydrokinesis, or Waterbending, much like her mother.
- Depth Adjustment: Her heritage also allows her to survive crushing depths.
- Enhanced Strength: and gives her above human strength (only in her mermaid form though).