Ares (mythology)

Ares was the Greek god of warfare, specifically the more barbaric parts such as slaughter and blood-lust. His sister (and fellow war-deity) was known as Athena and embodied the more honorable parts of warfare. 

The ancient Greeks had a love-hate relationship with Ares as they knew he was important yet were also fully aware of the more negative aspects of the deity, like almost all deities Ares is more accurately described as amoral rather than evil as he had both positive and negative traits (much like the concepts he embodied), though his negative traits are shown more often, and a number of people who study Greek mythology believe that Ares is the closest thing the Greek pantheon has to a "god of evil," as he is extremely brutal, even by Olympian standards, blanketing himself in the skins of his victims. For this, and many other reasons, he is greatly loathed by his fellow deities, who often speak negatively of him.

Trivia

 * His battle chariot is driven by Fear (Phobos) and Terror (Deimos).
 * He is known for having love affairs with Aphrodite (the goddess of love). Aphrodite is already married to Hephaestus, the god of craftmanship.