Nemesis

nemesis (nm-ss)
n. pl. nem·e·ses (-sz)
1. A source of harm or ruin: Uncritical trust is my nemesis.
2. Retributive justice in its execution or outcome: To follow the proposed course of action is to invite nemesis.
3. An opponent that cannot be beaten or overcome.
4. One that inflicts retribution or vengeance.
5. Nemesis Greek Mythology The goddess of retributive justice or vengeance.

In Greek mythology, Nemesis (Greek, Νέμεσις), also called Rhamnousia/Rhamnusia ("the goddess of Rhamnous") at her sanctuary at Rhamnous, north of Marathon, was the spirit of divine retribution against those who succumb to hubris (arrogance before the gods). The Greeks personified vengeful fate as a remorseless goddess: the goddess of revenge. The name Nemesis is related to the Greek word νέμειν [némein], meaning "to give what is due".[1] She was associated with the Roman Invidia.

http://en.wikipedia.org/wiki/Nemesis_(mythology)