In Vajrayana Buddhism, a Wisdom King (Sanskrit vidyarāja, Jp. 明王 myō-ō) is the third type of deity after Buddhas and bodhisattvas. The Sanskit name literally "king of knowledge", while the Chinese characters mean "bright king", leading to wide array of alternative English names including Guardian King, Radiant King, etc.
The female counterparts of Wisdom Kings are known as Wisdom Queens (Jp. 明妃 myōhi), although the distinction is often ignored.
According to the esoteric doctrine of the Three Wheels, whereas Buddhas represent pure concepts and bodhisattvas teach through compassion, Wisdom Kings are the embodiment of the wheel of injunction and teach through fear, shocking nonbelievers into faith.