The fourth incarnation of Lord Vishnu was Narasimha Avatar who came to earth to save his devotee Prahlad and end the torment of a demon king Hiranyakashipu. According to scriptures, legends, and beliefs, Hiranyakashipu was a demon ruler who had the privilege of not being killed by any human, god, or even animal, and thus came to think of himself as great. He instructed all to worship him, not the gods, and he alone was truly immortal. But his anger did not work in front of his son Prahlad who worshiped Lord Vishnu with all his heart. And so, Hiranyakshapu tried to kill his own son Prahlad, and before he could do so, Lord Vishnu took the form of Narasimha, half man and half lion, and with his powerful grip overran Hiranyakshapu’s rule. Ended.