Melkor aka Morgoth and Sauron

[I'm Murrin]

Melkor was evil from the beginning

Melkor did not begin evil. He was just as any other Ainur, but he performed one simple act of rebellion - sowing discord into the song - and then from that, while he had many chances to turn back, continued toward worse and worse acts against his creator and the rest of his kind, until he became evil because of this. The more his attempts to impose his own designs upon creation were resisted, the stronger and darker his desires to do so became. He was driven to evil by his desire for power and control.

Sauron was corrupted by Melkor's influence - these other Ainur followed Melkor's lead in the song, and followed his designs thereafter, rather than conceiving ideas of their own. Sauron was corrupted by his desire for the power Morgoth offered him, and after Morgoth was defeated, Sauron continued to seek this power on his own.

[Grimm]

Melkor did not begin evil. He was just as any other Ainur, but he performed one simple act of rebellion - sowing discord into the song

The more his attempts to impose his own designs upon creation were resisted, the stronger and darker his desires to do so became. He was driven to evil by his desire for power and control.

Well said, Murrin! You have begun to sway my vote.

Grimm

[Ainulindale]

First their are some interesting replies above, and al ot of it touches on the answers, but let me see if I can bring slightly more clarity to the Melkor/Sauron debate.

The question is about who is more evil which is pretty hard to base, so it's a good thing Tolkien tells us himself here (notice my bolding of the relevant part):

"In all the deeds of Melkor the Morgoth upon Arda, in his vast works and in the deceits of his cunning, Sauron had a part, and was only less evil than his masters in that for long he served another and not himself. - Of the enemies, Valquenta, The Simarillion - JRR Tolkien

To go on further their is no question when both Sauron and Melkor were at their peak, Melkor was the more powerful he was the greatest of the Valar, and only Manwe rivaled him in individual ability as stated here:

"the mightiest of the those Ainur who came into the world was in the begining Melkor" Of the Valar, Valquenta, The Silmarillion - JRR Tolkien

And Iluvatar himself said:

" "Mighty are the Ainur, and mightiest among them is Melkor"

Their an be no question who is innately the more powerful, however at varying times during mythos it can be concluded that Sauron at times was more powerful than Morgoth, which is due to what was tocuhed on slightly by previous posts of Morgoths's corruption of Arda proper itself, in essence creating evil and this also is remarked on by Tolkien here:

"Sauron was 'greater', effectively, in the Second Age than Morgoth at the end of the First. Why? Because, though he was far smaller by natural stature, he had not yet fallen so low. Eventually he also squandered his power (of being) in the endeavour to gain control of others. But he was not obliged to expend so much of himself. To gain domination over Arda, Morgoth had let most of his being pass into the physical constituents of the Earth hence all things that were born on Earth and lived on and by it, beasts or plants or incarnate spirits, were liable to be stained. Morgoth at the time of the War of the Jewels had become permanently 'ncarnate: for this reason he was afraid, and waged the war almost entirely by means of devices, or of subordinates and dominated creatures.

Sauron, however, inherited the 'corruption' of Arda, and only spent his (much more limited) power on the Rings; for it was the creatures of earth, in their minds and wills, that he desired to dominate. In this way Sauron was also wiser than Melkor-Morgoth. Sauron was not a beginner of discord; and he probably knew more of the Music than did Melkor, whose mind had always been filled with his own plans and devices and gave little attention to other things.

Sauron's power was not (for example) in gold as such, but in a particular form or shape made of a particular portion of total gold. Morgoth's power was disseminated throughout Gold, if nowhere absolute (for he did not create Gold), it was nowhere absent" from Morgoth's Ring - JRR Tolkien

Here Tolkien flat out answers the question for us, and brings up the most relevant point, Sauron inherited Morgoths coruption of Arda, and in essence became the ultimate practioner of evil, but evil did not exist until Melkor birthed it himself in his song. Which is explained here again:

"Melkor was not just a local Evil on Earth, nor a Guardian Angel of Earth who had gone wrong: he was the Spirit of Evil, arising even before the making of Ea. His attempt to dominate the structure of Ea, and or Arda in particular, and alter the designs of Eru (which governed all the operations of the faithful Valar), had introduced evil, or a tendency to aberration from the design, into all the physical matter of Arda." - From Morgoths Ring - JRR Tolkien


In essence as Tolkien also states Middle Earth is Morgoth's Ring, and the existance of Evil is his legacy. I personally favor Sauron myself, as his will was to dominate life, where Melkor truly wanted to subvert life.

[High Lord Tolkien]

Yeah, Morgoth's Ring is an excellent read!
TONS of interesting tidbits.

[Warmark Troy]

Sauron and Melkor are two great enemies of Middle-Earth; each in his own way. Both have caused untold suffering and damage to its inhabitants, and although for a long time Sauron was Melkor's servant (and by that, "less evil", as Tolkien tells us in Morgoth's Ring), when he gained "independence" from his master he proved to be at least Melkor's equal in cruelty and malevolence. The difference between the nature of their evil is interesting: while Melkor seeks only to unmake Arda, sinking into what seems to be insanity further as he strives toward that goal, Sauron is not concerned with his master's quarrel with Eru; he merely seeks lordship and dominion over Middle-Earth, to eradicate all that would oppose him (especially Elves, whom he feared and hated because he could not subdue them).

Sauron was not inherently evil even while under Melkors dominion. After the fall of Melkor Sauron was captured and released because he repented. The Valar considered this repentence genuine (and they are good judges of character). Sauron didnt return to doing evil for a considerable time afterwards, probably around a millenia - while the Numenorean Empire grew.
Melkor sought to unmake Arda out of spite because he had lost his rightful position as chief of the Valar.

Sauron also had a big advantage Melkor did not have. He had it in the beginning(as can be seen from his corruption of Men in Atrabeth Finrod ah Andreth, and by his actions in Valinor when the Valar released him), but later on, when he needed it more, he lost it. Whether because he thought he did not need it or because he could not control himself thus anymore, we do not know. That advantage is cunning, lies and deceit. Sauron mastered these skills well while under Melkor, when he wore the form of an evil sorcerer, and later on those skills literally saved his existence and proved to be the end of existence for others.

This is not true, Sauron was taught the skills of deceit by Melkor. Melkors lasting fruit is dishonesty and it stains relationships forever, even in the Undying Lands lies and hatred are concepts that are embadded in society. It is mentioned that this is his legacy after his destruction.

Now the scope of Melkor's "influence" is very large indeed: He brought discord into the Song, thus ensuring that Eru's original plans for Arda can never be fulfilled ere the End; he fought the Valar in the Beginning for lordship and damaged much of the young world, further marring it; he caused untold suffering to the Elves, first by deceit and lies he spread in Valinor, fueling Curufinwe's desire to leave, then by stealing the Silmarils and fighting with them for their posession.

Melkors influcence was intentional from the beginning, it is ther power Eru illuvatar bestowed upon him. Each of the Ainur has a function in the Choir. Melkor was the soloist and lead vocal. He was supposed to sing differently from everyone else, but it went to his head.
When Arda was made some of the Ainur came to the world to become Valar, each had a role - mostly elemental in nature. Melkors role was Shadow. Shadow was not evil in itself but it added depth to every other role. Melkor turned the world from '2d' spiritually speaking into '3d' thus shadow contained a part of every other power. So Melkor was a Valar jack-of-all-trades able to touch some of the power of every other Valar, but Melkor wanted to make something of Shadow in and of itself this personal and seperate force could be best described as 'evil'.

However, Sauron's own record is pretty impressive also: He caused much harm while in Melkor's service, and then when he remained behind in Middle Earth he quickly moved to establish a reign of terror of his own; cunning and seduction served him well in the creation of the Rings and the One Ring, which tipped the scales in his favor greatly. Ordinary wars and cruel persecutions of both Men and Elves in ME are typical for his personality profile, so I needn't mention them specifically. However, there is one thing which Sauron did, and which Melkor wanted to do, but never managed to do it; to utterly destroy a race or people.

Sauron was slow to turn back to evil. A long time passed between the years when Melkor fell and Sauron became the Dark Lord. However the seed of corruption was always there and he remembered the lessons Melkor had taught him. eventually he put the sorcery he had learned bac into practice.

The Numenoreans had as much in common with ordinary Men on the earth as the Elves did (except for the inevitable fact they were both mortal), so I believe it is fitting to separate them from the other Men as a race of their own. Their glory was somewhat shadowed before Sauron's arrival, true, but noone with a sane mind can claim that the events would happen like they did if Sauron's influence was not at work in Westernesse. An entire group of people, a glorious, powerful race was destroyed exclusively due to his machinations and influence.

Saurons corruption of Numenor was pivotal, but the Numenoreans had already corrupted themselves, Sauron only needed to give them a push in the wtrong direction. Its also considerably easier to corrupt men than any other race. Corrupting elves and dwarves is a far harder task, and one beyond Sauron.

But, I have dragged on for too long. Essentially, I would like to hear your opinions on this; Who was "more evil"? Can such a comparison be made in the first place? Is Melkor's power more important when determining the magnitude of their evil than Sauron's cold, hard logic and scheming? After all, Sauron did with falsehoold and deceptions in Numenor what no multitude of Melkor's Orcs and Dragons could. I await your contribution.

Melkor was considerably more evil. He invented evil and corrupted Sauron amongst others. It was Melkor who twisted the elves into orcs and the ents into trolls. It was Melkor who destroyed the Lamps, the Trees (with help) and denied the Silmarils to all others.
As far as deceptions are concerned Melkor deceived the world twice into releasing him from captivity after falling into the hands of the Valar. Sauron was released once from capture (excepting being released by Huor the Wolfhound while in wolf form) . Tolkien records that Sauron was so intimidated by the army of the Valar (with Noldor remnant and Vanyar in tow) that he genuinely repented.

[Zahir]

I'm not sure people are quite understanding the full scope of what harm Melkor wrought. There is literally no part of the world not marred because of him. He is the reason Men are 'fallen' in a way the Elves are not. He is directly responsible for the corruption of Sauron as well as the Balrogs. He created dragons, and Orcs. He committed the first murder in Valinor.

[Revan]

Yup, true what you all say. But one could also argue he had no choice. If you remember, the Valar were all created from parts of Iluvatar mind. Therefore Melkor was made to be what he is - if he was give another part, one of compassion, he would, theorically at least, be very different. Sauron on the other hand, had a complete freedom of choice. So which is the more evil, the one who is made to be as he is, or the one that chooses that path?

[High Lord Tolkien]

Yup, true what you all say. But one could also argue he had no choice. If you remember, the Valar were all created from parts of Iluvatar mind. Therefore Melkor was made to be what he is - if he was give another part, one of compassion, he would, theorically at least, be very different. Sauron on the other hand, had a complete freedom of choice. So which is the more evil, the one who is made to be as he is, or the one that chooses that path?

I wouldn't go that far.
He had a choice at the beginning like everyone else.
When Aule created the Dwarves Iluvatar gave the Dwarves the freedom to act independently from Aule.
This same freedon was given to the Valar as well.
During the Music of the Themes, why would Iluvatar get angry at Melkor if he knew what Melkor was going to do?
And throughout the Silmarilion Melkor was given choices but chose poorly each time.