Wakan Tanka, most often translated as "Great Spirit" or, more carefully, "Great Mystery", is the central sacred concept of Lakota religion, referring to the pervasive sacred power, wakan, that underlies and animates the whole of existence, encountered in the sky, the earth, the buffalo, the four directions and every other significant element of the Lakota world rather than confined to a single distant heavenly throne.
The early twentieth-century ethnographer James R. Walker, working closely with Lakota religious leaders including the holy man George Sword, recorded an influential systematic account describing Wakan Tanka as encompassing sixteen distinct wakan beings and forces organised in a structured hierarchy, with four "Superior" gods, Wi the sun, Skan the sky, Maka the earth and Inyan the rock, at its foundation, suggesting that Lakota theology, at least as recorded through Walker's collaborators, held a considerably more structured and specific cosmology than the single vague "Great Spirit" label common in popular non-Native summaries. Wakan Tanka functions in Lakota prayer and ceremony, including the sacred pipe rite and the sun dance, as the ultimate power addressed and thanked, encompassing every specific spirit invoked within these rites as expressions of the same underlying sacred mystery.