Heruka (Sanskrit; Tib.khrag 'thung), is the name of a categorization of wrathful deities, cultivated beings in Vajrayana Buddhism that foster a fierce countenance to reward sentient beings. In China and Japan, it was called as Wisdom King. Herukas exemplify the incarnation of indivisible delight and voidness. They resemble as yidam or meditational deities in tantric sadhana, often placed in a mandala and accompanied by a yab-yum consort. Heruka is a Sanskrit word that has a interger of contrasting meanings relying on the tantra .
In the Tibetan language the word heruka is interpreted as drag tung which meant blood drinker. When heruka is used in art and iconography it mainly has three contrasting meanings as found below. In the Nyingma (Old) Tradition Heruka ordinarily refers to any male-meditational deity, wrathful in inception , usually with three faces, six arms, four legs, wings and a consort. There are eight noticeable Nyingma Heruka deities. Some deities with a semi-peaceful - semi-wrathful occurrence, arising from distinct Revealed Treasure Traditions cited to as Heruka. In the Sarma (New) Traditions of Sakya, Kagyu, Jonang and others, the term Heruka usually raises to any complex Anuttarayoga male-meditational deity, peaceful or wrathful, that emerges in a shortened form with one face, two arms and a consort. In the Gelug Tradition (also belonging to the Sarma) the term Heruka almost exclusively identifies to the complex meditational deity Chakrasamvara in all features.