In Celtic mythology, the figure known as the King of the Otherworld, ruling over the fairies, is often referred to as Aengus or Manannan mac Lir. These characters embody the mystical and enchanting aspects of the fairy realm. They represent themes of magic, transformation, and the complex relationship between mortals and otherworldly beings. These legends highlight the importance of the supernatural in Celtic culture, illustrating the cycles of nature and the interconnectedness between the human world and mystical dimensions.