The Nazgûl were they, the Ringwraiths, the Úlairi, the Enemy's most terrible servants; darkness went with them, and they cried with the voices of death. The Nazgûl or Ringwraiths (Quenya plural: Úlairi) first appeared in the Second Age, according to the "Akallabêth" in The Silmarillion.
We have to defer to the Professor here, the Nazgul were his most powerful servants. The Mouth of Sauron is probably next, being a Black Numenorean and a sorcerer and had a high ranking position as Lieutenant of Barad-dur.
The Men of Darkness, also known as the Men of Shadow, were the Men of the east of Middle-earth who fell under the dominion of Morgoth in the First Age or were dominated by Sauron and worshipped him in the Second Age. In the Third Age they were moved by him against the Dúnedain.
The Nazgûl (Black Speech: Ringwraiths, sometimes written Ring-wraiths), also known as the Nine Riders or Black Riders (or simply the Nine), were Sauron's "most terrible servants" in Middle-earth. They were mortal Men who had been turned into wraiths by their Nine Rings of power.
Dwarves proved too resilient to bend to his will, but he enslaved Men as the Nazgûl, his most feared servants. Orcs and Trolls became his servants, along with Easterlings and men of Harad.
Ranking the 9 Powerful Monsters of Morgoth - LOTR Lore
Why did Sauron fear Aragorn?
Bloodlines are very important in Tolkien's stories, and it makes a lot of sense that Sauron would fear the great-grandson of the man who cut off his hand. Aragorn carried the blood of Numenor with him. His genetic connection to the heroes of the Second Age established him as a dangerous opponent of Sauron.
It revealed Adar no longer serves Sauron, as we initially thought the mutilated elf might. Throughout The Rings of Power, we've slowly uncovered Adar's true identity. The show has offered us insight into the one-time elf, his origins, and why the otherwise hateful orcs adore Adar as they do.
Lords of Middle-earth gives the Shadow player alternate versions of the two Sauron Minions (The Witch-king and The Mouth of Sauron) as well as two Lesser Minions (Gothmog and the Balrog of Moria) to further his plans.
The last of the great Dragons, Smaug held allegiance to no one, with sloth and greed being his only masters. Near the end of the Watchful Peace, however, Smaug secretly became the ally of Sauron, who had enticed him with promises of wealth and power.
Morgoth was the first Dark Lord, and Sauron was his most loyal servant in the First Age. While the two were allies, their goals were different. Morgoth sought to destroy Middle-earth, which Sauron sought to control.
Sauron was once a wise Maia who valued order but was corrupted by Morgoth and became his first lieutenant wishing to assist Morgoth in order to create the world he saw fit.
While not appearing in the film series (most likely because he no longer existed in the world at the time of the said series because of his banishment to the Void in the War of Wrath in The Silmarillion), Morgoth's most powerful servants, such as Sauron, still thrive, and Morgoth was mentioned in The Lord of the Rings ...
Morgoth, the first to reign terror upon Middle-earth, was more powerful than Sauron and commanded an army of dragons and Balrogs. While both Morgoth and Sauron were cunning, Morgoth's rule and terror lasted longer and his corruption spread further, making him more formidable in the Lord of the Rings universe.
Mainly Eru for going against his will and siding with Morgoth. After the fall of Morgoth and Sauron's rise to power his primary nemesis would be a collection of leaders who opposed him: Gil-Galad, Elrond, Cirdan, Galadriel, Celeborn, the line of Elros and the Numenoreans.
In The Lord of the Rings, it is said that had Galadriel chosen to use her powers for evil instead of good, she would have been even more destructive and terrifying than Sauron himself. Galadriel was the greatest and most powerful of all Elves in Middle Earth in the Third Age.
The Mouth of Sauron was one of Sauron's most devoted servants. During LOTR, he was the lieutenant of the Tower of Barad-dûr and was Sauron's personal emissary and herald. His early history has never been told, but he was one of the Black Númenóreans who chose to worship Sauron and enter his service.
Smaug could easily have cut through the armies of Mordor, and delayed the invasion of Middle-earth by years. So it wasn't in Sauron's interest to take on the dragon, but that doesn't mean he saw it as a lost cause, as he fully planned on creating an alliance.
"So I think in his pitch to Galadriel, it cannot mean that he loves her or that there's any kind of romantic relationship. There should be no ambiguity around the fact that Sauron is evil — he's terrible, and he's using Galadriel to enhance his power."
Morgoth is the more powerful of the two. Morgoth was the mightiest of the Valar, a group whose weakest member would outpace Sauron. However, there are some circumstances and eras in which Sauron would win the day. Morgoth was born far beyond Sauron but lost and surrendered much of his power.
A mysterious individual of the Second Age was referred to as Adar, or "Lord-father", by Orcs, presumably because, according to Galadriel, of his status as one of the Moriondor, the first Elves to be captured and tortured by Morgoth.
When Halbrand and Galadriel captured Adar, Adar seemed not to recognize Halbrand as Sauron. Adar also claimed to have killed Sauron after watching Sauron experiment on the orcs, whom Adar sees as his children. It's possible Adar was pretending not to recognize Sauron as part of a ruse.
Adar, therefore, seems to honestly believe he killed the Dark Lord. He's almost certainly mistaken. Sauron is one of the Maiar - angelic and immortal spirits from the beginning of time. Since the Maiar are divine, primordial beings, they don't die in the traditional sense.
