- "Before them went a great cavalry of horsemen moving like ordered shadows, and at there head was one greater than all the rest: a rider, all in black, save that on his hooded head he wore a helm like a crown that flickered with a perilous light."
- —The Two Towers: "The Stairs of Cirith Ungol"
The Minas Morgul Cavalry is a descriptive term (not used by Tolkien) to describe the mounted troops that rode out with the Witch-king of Angmar from Minas Morgul to lead Sauron's armies to war. Tolkien referred only to "a great cavalry of horsemen."
In The Lord of The Rings, "The Two Towers", a great cavalry of horsemen rode out from Minas Morgul with The Witch-King himself ahead of them, while Frodo watched. It's unknown whether they were mounted orcs, men, or both, or whether (if men) they were Easterlings, Southrons, or men originally quartered at Minas Morgul itself.
In The Lord of The Rings, "The Return of The King", when Faramir led a retreat to Minas Tirith after the Battle of Osgiliath, "horsemen of the Enemy" (perhaps the horsemen from Minas Morgul) charged toward them, with orcs following them. But Haradrim were also present, and among them was a "mounted champion", so the horsemen may have been a Southron cavalry, with possible Orc-horse riders, or there may have been more than two groups of horsemen present: one from Minas Morgul, and another from Harad.
It may also be possible that who ever they were, that they were also present during The Battle of the Pelennor Fields particularly among the legions of Minas Morgul against the walls of Minas Tirith and that likely they like the rest of the enemy were all but killed off by the forces of Gondor since Aragorn II Elessar arrived.
Portrayal in Adaptations
The Morgul Horsemen did not make an appearance in any of Peter Jackson's Films. They were added to the The Lord of the Rings Strategy Battle Game, under the name "Morgul Knights."
In that game their armor appears to be similar to that of The Mouth of Sauron, suggesting a Black Numenoreans influence. They carry either swords or spears with triangular shields, and their horses are also well-armored, similar to real horse armor during the middle-ages and one could even argue that the Morgul knights are a corrupted reflection of the knights of Gondor, in particular Dol Amroth.