King Mardan, also known as "The Holy One", is a giant fish met in the large body of water in the Fish Monster Swamp of the Rainbow Butterfly Wood. He can be caught with a Poison Apple and is responsible for the lost Firbits, who were bewitched under his spell.
King Mardan appears to be a giant purple fish with huge green eyes, long yellow eyelashes and a big grin. He also has a very flamboyant nature, with cartoon hearts coming from his eyes when he blinks. His appearance and mannerisms lead Monica to mistake him for a female, and she expresses shock when he reveals himself to be male.
"King Mardan" also refers to a scoop which may be obtained by taking a photo of him at any time before giving him a Priscleen fish.
King Mardan's name and appearance are a reference to the Mardan Garayan, a fish which can be caught in the first Dark Cloud game (as well as in Dark Chronicle).