[Man-of-the-Wold]

Of the 19 "Rings of Power," Sauron had a hand in making 16 of them. Beyond these there were supposedly various "lesser rings," the manufacture of which had mostly preceded Sauron's assistance to the Gwaith-i-Mirdain, the Jewel-smiths of Eregion; these lesser rings, Sauron either came to hoard or to give away as tokens, and doubtless the Elves preserved some. The lesser rings were not necessarily under the sway of the One Ring, but also they do not seem to have conveyed any particularly great abilities or invisibility, nor give indefinite life to mortals.

Of the Three Rings of Power that Sauron did not touch, these were given by Celebrimbor (their maker) in order of greatness to: Gil-Galad, Galadriel and Cirdan (or Cirdan's came indirectly through Gil-Galad). This happened either just before or right after Sauron made the One Ring, as immediately perceived by Celebrimbor and the other Elven-smiths. Therefore, the three Elven ring bearers could not generally wear, openly use or effectively wield their Rings, even though they did derive some power and strength from possessing them, in the Second Age, during which time Gil-Galad gave Vilya to Elrond. In the Third Age, the three Elven lords (not realy "kings" any) did tremendous work with The Three, although Cirdan had relatively little use for his, and gave it to Mithrandir c. 1000 TA.

Of the 16 other Rings of Power, one was supposedly given directly by Celebrimbor to Durin's heir in Moria, probably before the making of The One, and the Dwarves of Khazad-dum were then doubtless warned against using it significantly while Sauron had The One. I find this tradition of the Dwarves much more credible than having Durin's Folk receive a ring from Sauron.

Of the remaining 15, Sauron sought out a leader from among the other six houses of the Dwarves, in the mid-Second Age. Presumably, Gundabad was then still an ancestral home of one such group. A royal branch of the houses associated with Belegost and Nogrod likely still maintained a presence in the Blue Mountains or elsewhere, even if most of their population had joined the Dwarves of Moria. And perhaps, each of the other three dwarf houses had once existed in the Mountains of Mordor, the Mountains of Mirkwood, the Grey Mountains or further east, before Sauron's dominion. But Sauron could not dominate dwarves directly through their Rings, nor did any dwarf escape death by bearing a Ring. Nevertheless, the Seven rings did give the Dwarves power after their own hearts, in amassing further riches, but they likewise contributed to the decline of the Dwarven Houses. Their fastnesses and weakeness seemed to be more easily perceived by Sauron or by Dragons, and the Rings accentuated the rage, paranoia, bitterness and avarice that were fatal flaws of the Dwarves to begin with. By the end of the Second Age, the House of Durin may have been the only one still existing with any integrity, and Sauron had recovered two of the six that he had given away, and four were consumed by Dragons (or possibly later in the Third Age). The one held by Durin's line was eventually taken from Thrain, Thorin's father in Dol Guldor (2845 TA).

The remaining Nine were given to Men at some point during the middle Second Age. The recipients were supposedly kings, sorcerers and/or warriors, who became greater still, and lived (seemingly) for great spans of time, as Sauron had no doubt promised, before they were fully enthralled by him as shadows, and Sauron held their rings, until giving them back to them before the War of the Rings. Doubtless, besides the Nazgul themselves, Sauron gained a lasting hold on the allegiance of the nations formerly ruled by those ring-bearers. Three of them were Numenorean lords who had realms at Umbar or farther south. If they were already Black Numenoreans at the time, that would suggest that Sauron did not necessarily give out the Nine immediately after the overthrow of Eregion, but possibly centuries later. Alternatively, these three became forerunners of what were eventually called "Black Numenoreans" or the King's Men in Middle-Earth. Angmar, the chief of the Nine, was supposed a great Numenorean sorcerer. Possibly one of the other six came from among the pre-Dunlendish Men of the White Mountains, who later worshipped Sauron. Probably, as least three were Easterlings, related to those that had allied with Morgoth. The Black Rider that comes to Hobbiton, had once been an Easterling. The other two, I suspect would be out of Nurn, Haradrim or some places south of Mordor. It does not seem that Sauron would have had much chance to encounter Andunaic groups in the North during the Second Age. So, I discount that any former Northman became Nazgul.