Arthindol

Arthindol was a powerful lich, the Eternal Master of Thay, and the Zulkir of Necromancy. He mainly resided in the Doomvault.

History
Arthindol was a human who sought great power at any cost. It is unknown when he joined the Red Wizards and when his natural death occurred. However, it is known he was raised as a lich and took residence in the Doomvault, a horrible dungeon deep under Thay.

As Eternal Master of Thay, Arthindol was feared and largely despised. The loyalty of the Red Wizards was very shaky, as many in the Doomvault were quick to betray Arthindol's wishes in order to preserve themselves. The Red Wizard Hamun Kost actively sought Arthindol's death, presumably in order to take the spot of Eternal Master for himself.

Death
Zero Uchiha, Rose, and Lucien Lachance encountered Arthindol in his phylactery vault within the Doomvault. Guided by the advise of Hamun Kost, the party was able to shut down Arthindol's phylacteries and destroy his physical form, destroying him for good.

After this battle, Arthindol's ghost was able to briefly manifest, and he answered questions the party had. He revealed to Zero and Lucien important information about their past, telling Zero of Aincrad, Kalru Uchiha, and the true nature of the Great Ruby of Kalru.

To Lucien, he told him of the origins of the Gillil Clan; of how he aided Kalru Uchiha in creating a "key" to hide the city of Aincrad. He mated with a tribe of elven maidens and made a nomadic tribe, ordering them to never stop traveling and to always protect the "key," keeping it a secret from all of those except the Wise Women in the clan.