Originally, the Daevas, together with the Ahuras, were a classification of gods and spirits. In later Persian religion they were degraded to a lesser kind of beings, demons. The word 'devil' is derived from their name.
The seven archdemons of the Daevas are: Aesma Daeva, Aka Manah, Indra, Nanghaithya, Saurva, Tawrich and Zarich.