Spotted Tail (Siŋt Glesk, birth name T’at’aŋka Napca “Jumping Buffalo”; born c. 1823 – died August 5, 1881) was a Brul Lakota tribal chief. He was known as “The Orphan Negotiator.”

Although a great warrior in his youth, and having taken part in the Grattan massacre, he declined to participate in Red Cloud’s War. He had become convinced of the futility of opposing the white incursions into his homeland; he became a statesman, speaking for peace and defending the rights of his tribe.

He made several trips to Washington, D.C. in the 1870s to represent his people, and was noted for his interest in bringing education to the Sioux.