It was the Barbarian King and his horde of men who were the ones who nearly killed Kratos and the entire Spartan army. However when Kratos summoned Ares, the Barbarian King and his men were all killed.
Reappearance in God Of War II
While the Barbarian King is merely a back-referenced, minor character in God of War, he makes a re-appearance in God of War II: Divine Retribution. He tells Kratos that he has fought his way out of Hades, and he too seeks an audience with the Sisters Of Fate in order to return to the day when he was defeated by Kratos. A boss-fight ultimately ensues, after which the victorious Kratos claims the Barbarian Hammer as his reward.