Saga

In his first appearance, Saga presided the event in which Pegasus Seiya acquired the status of Saint. In the anime adaptation, he was introduced in identical manner, in episode 1. Saga served as the main antagonist for the Sanctuary arc. Being an excellent strategist, Saga managed to put himself in control of the sanctuary (though unfairly) for many years. Before the final showdown between himself and Pegasus Seiya, Saga was portrayed as a mysterious being with his facial features hidden from view. Saga is often described by other characters as someone with the kindness of an angel but with the darkness of a demon.

This ambivalence ended up creating a split personality: a good Saga that was extremely loyal to Athena and an evil one that keep the control of the body most of the time and killed the previous Pope to steal his place. Sometimes it is hinted that the creation of his "bad" personality had the influence of some external force, although nothing was clearly stated. When it takes the control of Saga's body, his hair turn from blond to jet-black (the color schemes were altered for the anime, in which Saga's normally blue hair turned light grey). Saga's two "sides", can also communicate between them : in a dialogue the good Saga reproaches his evil "side" to have forced him to hurt Athena. (Source: Wikipedia)