Why was the Greek goddess Pandora created?

Pandora was not a goddess - she was supposedly the first woman on earth.

She was created by Hephaestus the black smith after he was ordered by Zeus to make a woman. Zeus ordered Hephaestus to do this, because he was angry with Prometheus, who had given mankind (which at this point was made up entirely of men) fire. He wanted to punish them in the worst possible way he could think of. So he made a woman.