Edgar (unofficial)

King's Quest II: Romancing the Stones
According to the unofficial alternate KQ2 timeline Edgar never became the heir of Daventry, and it was said that he and Rosella ultimately moved to Etheria, and King Graham had to look for an heir elsewhere, choosing Connor.

King's Quest IX: It Takes Two to Tangle
He is one of the protagonists in the novelization of the canceled game King's Quest IX: It Takes Two to Tangle.===