Magician Hydrogen is a curse fiend man from Gateway Castle then the Region of Water in Xanth. He was first mentioned in Demons Don't Dream.
Hydrogen is the husband of Bec on Call and an ancestor of Morris.
Hydrogen helped the Curse Friends obtain their powers by learning the secret of modifying talents. He defeated Loudspeaker who was using his talent against their people, creating the Forbidden Regions in the process, and hid the secret for the good of Xanth. He is an ancestor of the merfolk in the Water Wing.
Novels: Demons Don't Dream, Swell Foop