This empire on the continent of Venetia is ruled by a nobility of dragonborn.

The nobles of Hydrus all believe themselves to be the descendants of a particular ancient red dragon. The nobility worship this being as a cult. From the nobility, an emperor of Hydrus is crowned. In order to take the throne a new emperor must fight the previous one. Korz-Ro is the name of the current emperor.

In the past century, the mage Mordenkainen help to liberate the island of Robur Virtus from Hydrus.