Günther Prozen

Possibly also translated as Günther Proitzen. This is favored by Shogakukan a few places. Also loses his umlauts a lot, in which case you should type Guenther.

Posed as a Guylos-tastic royal dude and regent to the current heir, but totally had other plans.

Zenebas' son, Camford's younger half-brother, and would-be ruler of the Neo Zenebas Empire. Except he got shot (and mortally wounded) by Karl Schwarz and exploded his Bloody Death Saurer all over the Guylos capital instead, which meant his son Wolff had to take over.

Not a sympathetic figure by any means, but not the Total Abusive Bastard a lot of anime fandom paints him as—Prozen, more accurately, was completely and ruthlessly devoted to recreating an idealistic version of the nation built by a father he never met.