Kurkesh is an ogrespirit, infesting ancient ruins on Shandalar.
If little is known of the Onakke, an ancient civilization of Ogres said to be masters of dark arts and artifice, even less is known of Kurkesh. More than one traveler daring enough to pilfer Onakke ruins met their end at this vengeful spirit's hands. An archeologist who survived the ogre's ghost found evidence that Kurkesh might have been a powerful artificer in ancient times. It is known that Kurkesh poured dark arcane energy into his various creations.
It seems to be implied that Kurkesh is none other than the creator of the Chain Veil.
In Magic 2015/Duels of the Planeswalkers, the boss of Shandalar is called "Onakke Guardians", and is described as the spirit of a crazed ogre shaman. It uses the "Kurkesh, Onakke Ancient" art, but it is unknown if it is supposed to be the same being.