Sandro Botticelli, Mars and Venus, c. 1483, tempera on panel, 69 x 173 cm, National Gallery, London
Ares (Greek) or Mars (Roman) is the god of war. The son of Zeus/Jupiter and Hera/Juno, he is disliked by most of the gods and frequently in opposition with Athena/Minerva. He is one of Aphrodite/Venus's lovers, and they are caught together by her husband, Hephaestus/Vulcan.
Though he is typically portrayed as a young man, he can also be older. Aside from those symbols shown here, his attributes include a halberd and shield, and sometimes a wolf.