The 4th incarnation of Vishnu as a man-lion -which springs from its name – “nara” =man; “simha”= lion.
The demon Hiranyakashipu, after performing hard penance for about 10,000 years, acquired a boon. As a result of which he could be slain neither by man nor beast; inside or outside a place; in day or night; nor by any weapon. This all-powerful demon became a terror to the Gods and consequently approached Brahmă who directed them to Vishnu. Also , Prahlă, son of Hiranyakashipu , turned out to be staunch devotee of Vishnu. Once the demon king asked him, if Vishnu was present everywhere , why was he not visible in the pillar of the hall where they had assembled and saying he struck the pillar which broke asunder. No sooner he did that, the Narasimha sprang from the pillar at dusk and tore off the bossom of the demon with his sharp claws.
Some sculptures show this incident taking place inside a pillar and others show Narasimha with Hiranyakashipu on his lap tearing out his entrails.