Hylia (born as Celeste) was a Hylian goddess who was the leader of the army of light during the Demon War. Hylia began her life a common Hylian named Celeste during the final years of the Pre Hylia Era. As a young adult she developed a relationship with Chamdar Taliesin, her childhood friend. Celeste's life however would change forevermore when the Demonic forces of the Ma invaded thr ancient Hyrulean Continent. Lead by the demon king Demise the Ma won victory after victory in their quest to take the Triforce.
As the war threatened to destroy the chosen people of the Divine Triune, the Goddesses came to Celeste and chose her as their First Scion, the guardian of the surface world. Celeste was reborn as Hylia, the living goddess. Granted god like powers the newfound deity fought at Chamdar's side as they strove to turn back the tide of the demons. In order to protect the Triforce Hylia united the surviving Hylian's on a piece of land and sent it to the heavens, sending them and, secretly, the Triforce beyond the clouds. With the humans gone, she united the remaining surface tribes to battle Demise's forces.
During the final battle of the war, Demise and his forces confronted Hylia directly in the Battle of the Sealed Grounds. At the start of the conflict it appeared that Hylia was at the mercy of the Demise as the Demon King prepared to finish off his rival. At that moment however a Demon Lords named Malauth betrayed Demise and the army of light traped his forces within the Sealed Grounds crater. Chamdar came to Hylia's rescue using the sealing spike to bind Demise in a massive explosion of light. However after the battle had cleared Chamdar disappeared and was presumed killed in battle.
Despite the fact that she had won the war however, she knew that the seal could not hold forever and that Demise would undo everything she had accomplished. To prevent this Hylia discarded her divine power, her immortality, and the memories of her life as the Goddess so that she could use the Triforce to destroy Demise. In her final moments, Hylia entrusted Impa of the Sheikah tribe with the task of protecting her future incarnation.