Phobos was the son of Ares and Aphrodite and the brother of Deimos ('Fear'). His name means 'panic' and is the personification of the emotion felt in war. (Deimos as a name means more 'terror'; Phobos' name indicates rather the outward show of fear.) The two small satellites of the planet Mars (i.e. Ares) are named Deimos and Phobos.

In mythology, the brothers were constant 'satellites' of their father and often drove the chariot into battle. (The planetary brothers were discovered and named as recently as 1877 by the American astronomer Asaph Hall. The choice of names could hardly be better.)