The Red Mage
The true name and origin of the Red Mage is unknown. He had not been heard of prior to his incursion to at the northern end of Eden Valley. The first indication was when a red fungus, known as the Red Death, began sweeping through the valley destroying everything and everyone in it's path.
The Red Mage faced Alastair and Aiden in battle in Eden Valley, which resulted in his defeat, but also the death of Aiden. The Red Death was stopped, and the Mage retreated to his keep to the north to lick his wounds.
He returned briefly sometime later, opening a portal to abduct Alastair, and then about a year later attempted to do the same to Lisa. Ajay followed, and the Red Mage was finally killed by Ajay and Lisa - after resurrecting himself multiple times. It was only after his death that it was revealed that the Red Death was a powerful spell that collected the power from everything that was killed by the fungus.