noun

nemesis

A person or thing that brings about a deserved downfall.

The prosecutor becomes the corrupt mayor's nemesis by exposing his crimes.

Etymology

The Greek word names retribution and also its personification as a goddess. English applies the name to a person or force that brings a deserved reversal of fortune.

More examples

Her greed becomes her nemesis when investors uncover the fraud.
The records he falsified prove to be his nemesis.
In the end, the tyrant's cruelty was his nemesis.

Forms

nemesis · nemeses

retribution noun — Punishment deserved for a past wrongdoing.

Similar words

undoing: Names a cause of ruin, without implying deserved punishment.
downfall: Can name the ruin itself rather than its cause.