畸鸟是中新世至更新世北美洲及南美洲中非常巨大的猛禽。牠们与秃鹰是近亲，但却自立为一个畸鸟科（学名Teratornithidae）。

畸鸟现时已知有4个物种：

"Teratornis" olsoni是来自更新世的古巴，但其亲缘不明，甚至可能不是畸鸟。另外在厄瓜多尔尔西南部也有未描述的化石。

Teratorns (from the Greek Τερατορνις Teratornis, 'monster bird') are an extinct group of very large birds of prey that lived in North and South America from the Miocene to Pleistocene epochs. They include some of the largest known flying birds.