The Wraith of Sul-Senipul is the ghost of Sul-Senipul, the father of the Ashkhan Sul-Matuul. He resides in the Urshilaku Burial Caverns in the Ashlands on Vvardenfell. He carries his bow, the Bonebiter Bow of Sul-Senipul, which the Nerevarine must retrieve from him during the quest "Meet Sul-Matuul."
Sul-Senipul was the father of Sul-Matuul, the current Ashkhan of the Urshilaku Tribe, which resides nearby his cave in the Urshilaku Camp. Before his death, he was the Ashkhan of the Ashlanders himself.
During this part of the Main Quest, the Nerevarine seeks to gain the trust of the Urshilaku tribe and their Ashkhan, Sul-Matuul. They are given the task to retrieve Sul-Matuul's father's bow from within the tribe's Burial Caverns, in order to prove their worth. The Wraith of Sul-Senipul is killed in the process.