Who is on the Mercury Dime?

The woman on the Mercury Dime is Lady Liberty with a winged headdress called a Liberty Cap. The wings signify freedom.

The image looks very much like a picture of the Greek god Mercury who used his winged helmet to fly through the heavens. Because of that the coin was mistakenly called a "Mercury" dime almost from its first day in circulation, and the name has stuck for nearly a century.