So I was trying to come up with the list of the nazgul that's I've known throughout the game or can think of. Could anyone look at the list and correct me if I am wrong here, I was only able to come up with 8 out of the 9. I'm not sure if some of these enemies are just powerful cargul like mordorith or not.
1. The Witch-King (appears throughout the epic storyline in different forms starting from volume I)
2. The Lieutenant of Dol Guldur ( final boss of the level 65 raid, Barad Guldur)
3. The Bane of Rhun ( in an instance quest in the black root vale)
4. The Forsaken Reaver (final boss in 3-man Instance, Quays if Harlond)
5. The Black Blade of Lebenin ( final boss in 6-man instance, Dome of stars)
6. The Gloom if Nurn ( final boss in 6-man instance, silent streets)
7. High Sorcerer of Harad ( Boss 5 in the raid, throne of the dread terror)
8. Woe of Khand (Boss 5 in the raid, throne of the dread terror)
9. ???