Obligatory pedantry: "Angmar" was the name of the northern realm which the Lord of the Nazgul once ruled as the "Witch-King of Angmar". We don't know what his original name was, although I believe there's a reference to him being a Lord of Numenor somewhere. Tor.com recently had a nice overview of him: https://www.tor.com/2019/10/31/exploring-the-people-of-middl...

The only canonically named Ringwraith was Khamul, the Witch-king's number two. (Roleplaying game company Iron Crown Enterprises once put out some nice but totally unofficial names for all the Nazgul.)