Its my puppies name and shes a girl, however if it werent for her i would think of it more traditionally as a masculine name since it is the god of war. We spell it like the zodiac Aries which is what shes named for...so i do think Ares is a more masculine fit.
Ares is a nice name, but it can be for both boys and girls, like the names jessie, rene, chris (kris), aaron/erin. Ares is also the name of the Greek God of War (male).
It's a boy's name (according to my source below). My first impression made me think it was a boy's name before looking it up. It doesn't sound exclusively male, though, just predominantly so. Kind of like Tony- a male comes to mind first- but there are plenty of females named Toni.