Regis Lucis Caelum is a pivotal character in Final Fantasy XV, serving as the King of Lucis and the father of the game's protagonist, Noctis Lucis Caelum. As the ruler of Lucis, Regis is a wise and compassionate leader who is deeply committed to protecting his kingdom from the encroaching forces of the Niflheim Empire. His character is defined by his strong sense of duty and his love for his son, whom he prepares to succeed him as king. Despite his declining health, Regis remains a symbol of hope and resilience for his people, embodying the ideals of courage and sacrifice.