Sheena Fritz (シーナ・フリッツ Shīna Furittsu?) was the youngest daughter of Ymir Fritz the Founder. She would later become the namesake of the innermost wall of Karl Fritz's three Titan Walls, Wall Sheena.
Around 2,000 years ago, Sheena Fritz was born to the king of Eldia, Fritz and his slave and concubine Ymir, the first of the Titans, alongside her two sisters Maria and Rose. When her mother died after an assassination attempt on the Fritz King, immediately after her death, Sheena and her sisters were forced to eat their mother's corpse on the orders of their father in order to prevent the power of the Titans from being lost. It worked and she acquired the power of the Titans as did her sisters. She presumably aided her father's expansion of the Eldian Empire, and on his death bed was instructed to have as many children as possible and upon her own death, allow her spine to be eaten by her children so that her powers can be passed on, and that the process would be repeated again and again as the family line continued so Eldia could reign over the world.
Her powers were passed down to unknown successors as did her sisters, eventually splitting into the Nine Titans that would continue to serve Eldia. Over 1,800 years after the death of Ymir Fritz and her three daughters, Karl Fritz raised three concentric Walls on Paradis Island formed from countless Colossus Titans. These Walls would be named after Sheena and her sisters, with the innermost Wall being named after Sheena.