Father Time

"That is old Father Time, who was once a King in Overland. Now he has sunk down into the Deep Realm and lies dreaming of all the things that are done in the upper world. Many sink down and few return to the sunlit lands They say he will wake at the end of the world."

- Mullugutherum

Biography
Father Time was an ancient giant that once ruled the Ruined City of the Giants. At some point he sank down into Underland and was sleeping there when Eustace Scrubb, Jill Pole and Puddleglum found the lost prince. It is unknown what happend to him when Underland fell apart.

Trivia

 * Although not specifically said in The Silver Chair the understanding is that the Lady of the Green Kirtle enchanted Father Time into this sleep.
 * It is possible that when it is said that "he will wake at the end of the world" that this means that he will wake when the Lady of the Green Kirtle died, as that was the end of the world of Underland.