The Lunatic Magician (狂乱の魔術師 Kyōran no majutsu-shi) is the mage responsible for the creation of the dungeon on The Island. His actions make him the secondary antagonist of the manga Delicious in Dungeon.
The real identity of the Lunatic Magician is an elf called Thistle (シスル Shisuru) who served as a magician in the court of King Delgal during the Golden Age.