Since the name means “elf king,” it’s pretty obvious that Aubrey was originally used for men. It comes from the German Alberic: alb=elf; eric=king. It goes back a long way -- a twelfth century saint bore the name, and it was a very common men’s name in the Middle Ages and, after a drop, was revived again in the nineteenth century. The traditionally upscale British name reached its male peak in the US around the last turn of the century. In the US (and pretty much only the US) it started being used for girls in the ’60s and steadily rose until it started skyrocketing at the beginning of the twenty-first century to its current peak (right about when the male Aubrey dropped off the charts entirely). Some of its popularity is probably due to its similar sound to the also recently revived Audrey.