Ares

 Ares' (戦神・アレス Senjin Aresu''?), is the fierce and bloodthirsty god of war, who battled Athena and her Saints millennia ago, in the ages of myth. He appears only in The Lost Canvas - Anecdotes - Chapter Aquarius, and since Kurumada has never revealed Ares' appearance in his manga, Teshirogi employed an original design to portray the deity.

In Hypermyth
After the first battle between Poseidon and Athena, the god Ares and his Berserkers fought against this, which is said to have been the most violent holy war of antiquity.

Berserkers The four legions were on the ropes to the 58 men who were at that time. The death toll was not quantifiable, whereas Ares's army did not perceive any casualties. It was not until the Libra Gold Saint approved the use of the 12 weapons, that it was possible to defeat the Berserkers. Ares desperately fled the battlefield for Hell to plead for help to his uncle, Hades, which became the first war against the God of the Dead.

For some reason not yet revealed, Ares and his army were locked in Tartarus.

Penultimate Holy War (formerly Sage)
He was one of the three Gods in the fight against the sanctuary and was sealed. This God is allied with his uncle Hades (whom, it is said, provides the inhabitants of his kingdom, caused by war), and he is also related with Loki, Set, Kers, Kydoimos, Deimos, Phobos, Anteros among others.

Mythology
Ares was one of the children of Zeus and Hera and the God of War amongst the Olympians. While Athena is the goddess of battle strategy and cunning in times of strife, Ares by contrast is the god of war in terms of the sheer violence and bloodlust amidst the din of battle. Ares loves war for the sake of killing men on the battlefield, helping whichever nation he favors the most. In the Iliad, this makes him the most hated of all the Olympians.

Aside from his bloodthirsty behavior, Ares is also known for his relationship with Aphrodite, the goddess of love and beauty. She was originally given to Hephaestus by Zeus to be his wife, but she found Ares more attractive because of his savage temper and given that he was handsome. Hephaestus found out about their affair and caught them both in a net made from a certain metal and showed the two before the other Olympians. It was hilarious for some time until Zeus demanded that Hephaestus release them both. When Aphrodite fell in love with the mortal Adonis, Ares, in his anger created the Erymanthian Boar and sent it to kill his rival. Needless to say, those two were so madly in love, Ares even let Aphrodite borrow his war chariot.

Although he can strike down mortal enemies with ease, Ares always seems to be defeated by other supernatural opponents. It is said that Hercules defeated him twice, to the point where he removed every bit of armor off of Ares' body. Another time two giants placed Ares in a jar and he couldn't get out, and the most famous scene was during the Trojan War when Athena used Diomedes' spear to injur him badly that his shout of pain scared both Greek and Trojan alike. Even during the first ever Olympic games, Apollo was able to beat him at boxing.