Embassy of Barad Dur

[Keeper of Dol Guldur]

It's a stupid question, but what manner of creature or race were the Black Embassy that accompanied the Mouth of Sauron, the Black Riders who went with him? They weren't Nazgul, and they definitely weren't orcs. I mean, this question has been burning me for days. Were they other Black Numenoreans (which I would tend to be inclined toward), or were they those 'lesser wraithes' or something different entirely? I don't think it even mentions them anywhere else, so I have no idea.

[Rumil]

If I had to guess (I don't think you'll find an answer in LoTR), I'd agree with you that they were Black Numenoreans, though I do wonder how many still survived at this time. Perhaps they also included elite cavalry of Harad and the Easterlings who 'worked' for Sauron.

Of course Minas Morgul also had its own cavalry force, seen by Frodo as they marched out through Morgul Vale. I'd thought of these as the Witchking's guard cavalry, probably 'crueller than any orc' and maybe tasked with driving the hordes of orcs into battle.

After all, if Saruman had more sense than to trust his gates to the orcs, surely Sauron did too?

[Meoshi]

Remember that the people of Umbar were themselves Black Numenoreans, or King's Men. There were still many living in the City of the Corsairs.