Abu'l-Fayd Thawban ibn Ibrahim, the leading early Egyptian Sufi, associated with the doctrine of ma'rifa (gnosis). His death is given as 245/859 (some sources 248/861); he died near Giza and was buried in al-Qarafa, with his tombstone preserved. His tomb is a known visited site, but no two independent coordinate sources could be confirmed, so location is unpinned. (Sources: TDV 'Zünnûn el-Mısrî'; Wikipedia.)