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
Human men and women will not have a species in their entries. Also, if the surname of the character is the character's species, it was dropped.
If the character is a child, it will be in the description. The child will more than likely be an adult by this time in the Xanth series.
Many species are single gender, so their entries will not mention it. The species are Fury, Muse, basilisk, cenmaid, cenmare, cockatrice, dryad, maenad, sand witch, sandman, and woodwife. Harpies and nymphs are usually female, and fauns are usually male; but there have been a few exceptions that are noted.
In some instances, I have made educated guesses on gender, species, and some birth years.