Appearances: Fire and Ice, Double Trouble, Emma Rebel, Hocus Pocus, Pressure Cooker, In Hot Water, Wrong Side of the Tracks, Riding for a Fall, Unfathomable, Treasure Hunt, Mermaid Monster, Camping on Mako Island, Cleo vs. Charlotte, Irresistable, Visions, The Heat is On, The Gracie Code (Parts 1 and 2), Then There Were Four, Bubble, Bubble, Toil and Trouble, Reckless, Three's Company, Sea Change, Finale.
Charlotte is the new girl in town and is the girls' rival during series two. She enjoys various forms of art and appreciates the sciences. She is friendly at first but becomes jealous of Cleo's relationship with Lewis, so she constantly tries to be with him. After Cleo breaks up with Lewis Charlotte pursues him and eventually the two develop a relationship. She is very selfish, controlling and manipulative and gets paranoid very easily and becomes jealous of Cleo. She is later revealed to be the granddaughter of Gracie, one of the original three mermaids. She becomes the fourth mermaid herself, receiving all three of the powers. After this she becomes very dangerous when angry, especially when Lewis breaks up with her to be with Cleo. The 50 year full moon comes and Charlotte reveals to Lewis that that is how Gracie lost her powers. She plans to strip the other girls powers so that she will be the only special one for Lewis. But after being beaten by the girls, she loses her powers forever, and her friendship with Lewis and the other girls.