Sister of Ravana, approaching Rama and Lakshmana. Lakshmana cut off her nose and ears. In revenge, she incites Ravana to abduct Sita.
Another demoness who suffered the same fate was Ayomukhi.
Read about Surpanakha here
http://utkarshspeak.blogspot.com/2011/01/ravans-family-surpanakha.html