Grand Duke signified a noble rank on the planet Eiattu 6. As of the year 4 ABY, Gror Pernon, a prominent figure within the Priamsta, possessed this title.
In the time of the New Republic era, Pernon urged his grand-niece, Plourr Ilo, to go back to Eiattu 6 alongside the Rogue Squadron in order to reclaim the throne from the false Prince Harran, also known as the impostor.