Waterbius is a Valenic Waterbien regnal title, traditionally conferred to the leader of an Impatinum. The lines of Waterbe traditionally referred to as Waterbia are the Waterbia of the Impatinum Unistarch and of the Impatinum Waterbe, as well as the name of the FS WATERBIUS.

In typical usage, the title of Waterbius completely displaces the Waterbius' given name, instead being only referred to as Waterbius X, where X is the regnal number.