A Starsinger is a person capable of using the power of the Great Crystal in Final Fantasy Crystal Chronicles: Ring of Fates. At the fullest extent of her abilities, the Starsinger is able to manipulate the very flow of time and alter the fate of any person she desires by choosing from all the possible fates that "are etched into the Crystal".
Aleria, along with her daughter Chelinka, and Princess Tilika were the only Starsingers involved in the story of Ring of Fates, suggesting that the power of manipulating crystals was only granted to certain women of Clavat blood (Tilika being half-Clavat). King Kolka also states that Rebena Te Ra's monarchy is tied to the Great Crystal, so this may be a source of Tilika's power.