As depicted in the Rankin Bass adaptation of The Life and Adventures of Santa Claus
The King of the Sound Imps is an immortal, and the ruler of the Sound Imps.
He has wings on his feet, and has an anxious and careworn face.
The King was part of the Council of Immortals that bestowed upon Santa Claus the Mantle of Immortality. (The Life and Adventures of Santa Claus)