Manannan

An old, twisted and evil wizard who had the custom of kidnapping infant boys (usually one year olds, though he occasionally takes younger babies) and training them as his slaves. He is the brother of Mordack, and Hagatha.

One day, when his first slave was 18 years old, he was caught in Manannan's secret magic lab, reading his spells. Fearing that the boy would use his own spells against him, he immediately killed him and picked another infant. To prevent this danger from happen again, by choice killed all of his servants as they reached age eighteen and picked another. Sometimes he was forced to shorten the cycle for some of the more precocious slaves. He even promised some of the slaves freedom if they followed orders, but his near perpetual anger and punishment of minor mistakes was enough that he never kept his promises.

He despised ignorance in his slaves so he taught them how to read, but he would only bring them the books which felt there was no danger for him in the slave reading. He did not allow them to choose their own books out of his library.

For many years he reigned as the absolute ruler of the land of Llewdor, and under his leadership brigands, thieves and the like prospered. Manannan made a terrible error, however, in the choosing of his final servant, a baby boy who he named Gwydion. Gwydion was able to escape the clutches of Manannan, and learning several magic spells from The Sorcery of Old, was able to turn Manannan into a cat.

While Mannanan was not personally in control of the Three-headed Dragon, he enjoyed watching its path of destruction across the lands on its way to the Kingdom of Daventry from afar, because of his hate of humanity.

Mordack then, captured the royal family in order to try to get Alexander to reverse the spell, but the poor Prince had no idea how he could do it. Once Graham travelled there to rescue his family and was inside Mordack's castle, Manannan (the cat) tried to get in his way. Graham gave him a fish and then captured him in a bag.

After the defeat of his brother Mordack at the hands of King Graham of Daventry, Mananan was never seen or heard from again and his fate remains unknown. Derek Karlvaegen hopes Manannan starved to death inside the bag, and he certainly hopes he didn't escape.

His home in Llewdor was later occupied by Karlvaegen soon after Alexander's return home. Its from where he communicates with Earth via the Eye Between the Worlds.

Manannan in the Unofficial Games
In King's Quest II (AGDI), he is a brother in the Black Cloak Society, he had sent correspondance to Hagatha, asking about the plans of the Father.

According to King's Quest 2 �, he hired strange men to kidnap Alexander for him, rather than kidnapping Alexander himself.

In IA's King Quest 3 remake Manannan hires a woman to kidnap the Alexander for him rather than kidnapping Alexander himself. The woman brings him to dock where he is waiting. She asks for a reward from her master and is wiped out of existance. In this version of the story he also lies to Gwydion about his parents, saying that the lad had cursed his parents, and is lucky to be living in Manannan's house. During one of Manannan's journeys abroad leaving Gwydion alone, he visits his brother Mordack to discuss his plans to kill Alexander.

According to King's Quest ZZT, somehow after the events of King's Quest 5, Manannan escaped from the sack Graham left him in, and he somehow was able to escape Mordack's Island and return back to his home on the Island of Llewdor(as opposed to the continent of Tanalore). Prince Alexander found him there on his way to defeat his cousin Ravenlos, and attempted to kill him once and for all, finding a note he had written to Ravenlos on his body, as well as a key to a chest that contained a Teleport Spell, and scroll with the Cone of Cold spell.

However unbeknownst to Alexander he had only knocked Manannan unconcious, according to King's Quest ZZT 2. Manannan later made it to Tamir where he was captured by a giant. Alexander was looking through a keyhole to the Giant's house saw the Giant sitting at a table, with Manannan in a cage. Manannan was attempting to shock the giant, and the Giant was warning him not to do it again, or their would be consequences. However Alexander made too much noise and the giant found him outside of door, forcing Alexander to defend himself. The whereabouts of Manannan on the World of King's Quest after the era of King's Quest ZZT 2 is unknown.

Real world
Manannan was a celtic god son of Lir (usually known as Manannan MacLir) and god of sea and weather.

In KQ5 he is said to be the brother of Mordack.

In the official King's Quest Collection trivia program, and King's Quest Companion, Hagatha is said to be his sister. Though this fact is not brought up in any of the manuals or the official adventure games themselves.

In KQ2 (AGDI) that info is refrenced, and he is said to be the brother of Mordack and Hagatha. However this is strongly implied to be a connection to the Black Cloak Society, and not a family relationship.