|Full name:||Hieronymus de Kraaij|
|First Appearance:||Not yet|
|Abilities:||Creating objects out of thin air, materialising into an unkindness of ravens|
Currently, not much is known about his role in Ghost from the Sea, except that he resides in the Underworld.
Hieronymus is shown to be tall and slender. He holds a bird-beak shaped, pale mask on his face, with dark glasses. He also wears a broad-brimmed dark coloured hat, and a large dark coat with a belt around his middle. This belt also has a pocket, in which are kept items, probably. Furthermore, Hieronymus wears black gloves and boots.
At times, Hieronymus is also seen with a long, wooden staff. At the top of this staff is a small hourglass with wings attached to it.
It is unknown what lies underneath the costume.
On his reference sheet it is said that he is a rather enthusiastic fellow, but he is also tenacious and strong-willed. Furthermore, he is inventive and melancholic.
He seems to like alchemy and books, as those can give him the knowledge to find a way to cure the plague and exterminate it. His favourite birds are corvids, which was to be expected since he owns a rook. He also shows a liking for the lavender flower. One of his hobbies is playing the piano.
Things he does not like include rats and summer, but also being disturbed and losing people. He also shows a hatred for the plague, which isn't that much of a surprise since he is a plague doctor.
Hierooknymus is Hieronymus's pet rook. The relation between the two is unknown.