Lady Luck

Fortuna, called Tyche by the Greeks, is the goddess of fortune.
She represents more than just good fortune:

• With a rudder, she symbolises the divine guide, steering fate;
  
• With a ball or the wheel of time, she is a reminder that fortune, good or bad, never lasts;
• With the cornucopia also known as Plutus, or the horn of Amalthea, she represents the plentiful gifts of fortune.

I still haven't figured out what the stem in her hand (in this picture) is for though. Maybe just to scratch her own back from time to time (those wings are bound to tickle).