Mordack (unofficial)

Mordack appears in fan fiction, including fan games.

King's Quest 2: Romancing the Stones
In KQ2 (AGDI) he is said to be also the younger brother of Manannan and Hagatha.

King's Quest 3: To Heir is Human VGA
Manannan visits Mordack on his island in the unofficial King's Quest III (IA) to discuss his plans for Alexander. A few months after Alexander's return home he teleports into Manannan's House to retrieve his brother. He then burns the house down.

King's Quest Companion ZZT
In King's Quest ZZT, Ravenlos is said to be his cousin.