Ares is a fictional character, a deity appearing in American comic books published by Marvel Comics. The character is based on the Greek god of the same name. He first appeared in Thor (vol. 1) #129 (June 1966) and was created by Stan Lee and Jack Kirby. Ares has commonly appeared as an enemy of Thor and Hercules and starred in his own self-titled series in 2006.
Ares, the Greek God of War, was initially depicted as a villain in the Marvel Universe, opposing Thor, Hercules and the Avengers. Early on, his influence on Earth was less direct as he created an organization known as the "Warhawks" and used them to create war on Earth.
Source: Wikipedia, "[en.wikipedia.org/wiki/Ares_%28Marvel_Comics%29 Ares (Marvel Comics)]", available under the CC-BY-SA License.