Virudhaka

Virudhaka is the prince of Kosala. Later he becomes the king. He is sometimes called Prince Crystal due to the Lapis Lazuli set in his forehead. After learning of his mother's true caste, he ostracizes her to the slave quarters and later orders her to be killed with the other slaves when plague breaks out among them. For tricking his father, Virudhaka begins a gradual extermination of Buddha's tribe until Buddha shows him that all he's accomplished is to increase the suffering he already felt. (Source: Wikipedia)