Ares

From the Soulcalibur Wiki

Ares (also known as "Palgaea") is the Greek God of War, who is is trying to take Soul Edge for his own purposes. He commanded the Grand Priest of the Fygul Cestemus sect, Kunpaetku, to create a golem to help find him. Although Kunpaetku created Astaroth in hopes of taking Soul Edge for himself, he didn't know that Ares, to assure Astaroth's loyalty, implanted Ker, the Agent of Death, inside him.

In the God of War series, Ares is killed by Kratos in the first installment, who then goes on to take Ares' mantle as the Ancient Greek God of War. It is unknown how this influences events in the Soul series, especially since Kratos lacked a back-story in Broken Destiny.