Narasimha Destroys Hiranyakashipu

Quick Answer

Vishnu took the half-man, half-lion form of Narasimha to kill the demon Hiranyakashipu, who had a boon making him nearly immortal. Narasimha appeared at twilight, on the threshold, placed the demon on his lap, and tore him apart with his claws, fulfilling every condition of the boon.