- The nine Nazgûl (sometimes called Ringwraiths) arose as Sauron's most powerful servants in the Second Age of Middle-earth. It is said that three of the Nine were originally "great lords" of Númenor. All were powerful mortal Men to whom Sauron each gave one of the nine Rings of Power that were forged for Men. It was Sauron's design to control the Nine Rings through the power of his One Ring, forged in secret for this purpose.
- In the Lord of the Rings trilogy by Tolkien, the Nine Nazgûl are sent to search the Shire for Frodo Baggins, and eventually track him down and chase the four Hobbits and Strider from Bree to the Lone-lands and to the Ford of Bruinen on their way to Rivendell. At Ford of Bruinen they lose their horses in a water wave raised by Elrond. Some of them return to their Master but some continue the journey to the north. After the Fellowship leaves Moria, three Nazgûl travel to Dol Guldur. One of them chased the Fellowship but Legolas kills his Fell-beast which crashed somewhere in Wold. They have few chances to catch the Ring bearer but they fail. In the battle of Pelennor fields all nine Nazgûl parcipate but the leader is defeated at the hands of Éowyn and Merry. Several days after, in the Battle of Morannon all Nazgûl collapse after the Ring is destroyed in the fires of Orodruin.
Though the mortal names of the nine have been mostly lost to history, some have come to be known individually by fearsome monikers. Among these are:
- The Witch-king of Angmar
- The Lieutenant of Dol Guldur
- The Black Blade of Lebennin
- The Gloom of Nurn
- The Reaver of Khand (The Woe of Khand) 
- The Grim Southron
- The Bane of Rhûn
- The Forsaken Reaver
- The High Sorcerer of Harad
Appearances of Nazgûl throughout the Lord of the Rings Online:
- Hobbit characters encounter a "Black Rider" during the beginning private instance in The Shire which leads to the shared introduction instance in Archet Dale. Another "Black Rider" appears toward the end of the beginning private instance for both Hobbits and Man characters. It is this Nazgûl that stabs the Ranger Amdir with a morgul-blade, leading to his transformation into a Cargûl later on in the storyline.
- In Bree-land, early in Book 1, "Stirrings in the Darkness", five of the Nazgûl appear at the end of the quest Instance: Unravelling the Thread, where they complete Amdir's transformation into one of the Cargûl.
- The Witch-king himself appears during dialogue in Instance: Othrongroth near the conclusion of Book 1.
- A Nazgûl appears near the end of Book 4, "Chasing Shadows", during the quest Instance: The Unmarked Trail, in a dialogue before the final fight. It is suggested by Legolas that this Nazgûl was once a king of Easterlings, and may thus be Khamûl, who also served as the Lieutenant of Dol Guldur.
- The same Nazgûl is found in the Misty Mountains during Volume I, Book 5, "The Last Refuge". It first appears at Gabilazan together with Skorgrím Dourhand in the quest Instance: The Last Refuge, and later in the Helegrod Treasury during the Instance: Fire and Ice.
- Three Nazgûl are encountered in Mirkwood in Volume II, Book 8, "Fortress of the Nazgûl", during the quest Instance: The Exchange. Their names are the Gloom of Nurn, the Black Blade of Lebennin and the Lieutenant of Dol Guldur. The latter is also found in the Sword-hall of Dol Guldur before the battle starts, although you won't fight him; he and his steed are also involved in a major battle on top of the tower of Barad Guldur.
- A Fell-rider Nazgûl appears in the quest Instance: The Battle of Dol Baran to speak with the Rohirrim defenders, but he leaves without entering combat.
- In The Great River, players discover a fallen Fell-beast and must search for the missing Nazgûl before he can find what he is looking for. Finally the Wounded Nazgûl appears in the quest Instance: Mists of Anduin, and he must be driven away.
- Another Fell-beast is observed in a Khundolar camp across the Undeep from the Wold. It is later present at an attack on Langhold, where it is ridden by The Reaver of Khand.
- While investigating Wódscrafen, players encounter the cause of the unrest among the dead - The Grim Southron.
- In the Eastfold of West Rohan, a Fell-rider Nazgûl appears in a brief drama sequence during the quest Instance: Breaking the Back of the Boar.
- The Bane of Rhûn appears in the Blackroot Vale of Gondor, during the quest Instance: The Shadow in Morthond.
- In the epic battle Hammer of Underworld when Grond breaks the gates, the Witch-king of Angmar speaks dark words and enters Minas Tirith. Also he appears in instance: The Darkest Hour as a leader of the Morgul-host, and is later defeated during the instance Death Comes for All.
- The Woe of Khand and The High Sorcerer of Harad comprise the penultimate boss encounter of Throne of the Dread Terror.
- "I call upon the Great Eye!"
-  ThePinion: "...the old Reaver needs to be changed to the Woe. When it came time to name one of the last ones we revealed (the Forsaken Reaver), we ended up having to ret-con that name as the Forsaken Reaver's original name didn't quite fit."