Cleo Massey (born 19 November 1993) is an Australian actress. She is known for her portrayal of Kim Sertori in the television series H2O: Just Add Water. Massey has been performing on TV and film since the age of 11. In 2010, she was cast in the feature-length film The Little Things (2010) directed by Neil McGregor.
Massey was born in Launceston, Tasmania. Her mother, Anna Waters-Massey, is an actress and acting teacher. Massey attended her classes while growing up. She has a younger brother, Joey.