Galaxina is a character from the anime series Sonic X, where she serves as a supporting figure in the Metarex story arc. She is a member of a humanoid, plant-like alien species and is specifically the older sister of the main character Cosmo. Her name, Galaxina, was given to her in the English dub of the series; in the original Japanese version, she is referred to simply as Cosmo's older sister or Onee-sama by other members of her clan.

In terms of background, Galaxina was a leader of the remaining survivors of her species after they were forced to flee their home planet. She was present at the birth of Cosmo, who was the last offspring of their mother, Earthia. During a naming ceremony for the newborn, Earthia's voice spoke telepathically to the group, declaring the baby's name to be Cosmo and identifying her as the last hope for the galaxy. Following this, Galaxina and her clan traveled through space on a large ship, which was powered by their mother, who had transformed into a giant tree-like state. Throughout this period, Galaxina and Cosmo developed a close bond, often visiting their mother together.

Personality-wise, Galaxina is portrayed as being very smart, sophisticated, and down-to-earth, contrasting somewhat with Cosmo's more timid and emotional nature. Despite her composed and wise demeanor, she is also tender and caring, and she worries a great deal about the well-being of her younger sister Cosmo and their mother Earthia. She is fully aware of the grave threat posed by the Metarex, the primary antagonists of the arc, and her primary motivation is the survival of her people and the protection of Cosmo, who carries the hopes of their entire species. Her role in the overarching story is ultimately a tragic one, as she is killed when the Metarex warship, the Scarship, launches a sudden and devastating attack on her clan's vessel. This attack results in the destruction of their ship and the death of nearly all of her kind, including Galaxina, with Cosmo being the sole survivor.

Key relationships define Galaxina's character. Her most significant bond is with her younger sister, Cosmo, for whom she acts as a guardian and mentor, explaining the importance of their mission to defeat the Metarex. She also shares a deep connection with her mother, Earthia, whose transformed state they visit. Other members of their clan, including Starla, Daisy, and Chrysanthemum, are her close allies and companions in their shared struggle. As a member of her species, Galaxina possesses inherent abilities related to her plant-like biology, which include the capacity to manipulate plant life. Her most notable abilities, however, are her wisdom, strong leadership qualities, and the sophisticated, caring nature that she demonstrates in guiding her clan through their perilous journey.