In the beliefs of the Variags and the men of Khand, the Khûdriag-Ata was a holy or demi-god like man, chosen by the Tumrakhi and giftet with immortality.
In fact Khûdriag-Ata was a role or masquerade invented by Sauron to deceive his mannish followers.The part was usually played by The ninth of the Nazgûl.