A god of the Eldar in the fictional Warhammer 40,000 universe, Khaela Mensha Khaine, normally abbreviated to Khaine, is associated with battle, war and conflict. Many scholars believe him to be a manifestation of the Eldar's racial passion as manifested in battle and warfare.

Khaine is also believed to have been assaulted, defeated, and dominated by Slaanesh, the newly-awakened Chaos god of pleasure and passion sometime after his (Slaanesh's) awakening in the 29th millenium (Imperial Calendar). Following this, Khorne the Blood God, patron of war and murder, battled Slaanesh for Khaine, rightly claiming the Eldar deity as belonging (at least partially) to him. During their struggle, Khaine escaped and divided his spiritual essence into the bodies of many of the Eldar race, who in turn became his physical manifestations - the dread Avatars of Khaine - who go before the Eldar in time of war, wielding the might of the War God himself. It is believed that there is one Avatar to each Eldar Craftworld.

Eldar Aspect Warriors are called to embody different aspects of Khaine through long training and conditioning, fulfilling different combat roles related to these aspects. The greatest Eldar warriors may, if the need arises, be called upon to become an Avatar of Khaine, one of the most powerful abilities/units the Eldar posess.

Because the Avatar is technically considered a Daemonic entity by at least some of the games using the setting, it is most likely that Khaine is a Warp entity. He does not appear to be as power-hungry and demonstrably evil as some others of this ilk (Slaanesh, Nurgle, Tzeentch and Khorne spring to mind), however.