The model for Sauron is Derek Medlin and the reference photographer David Vance
Sauron. The Dark Lord. Once an angelic spirit called a Maiar who was corrupted by an evil greater than himself, an evil so destructive that it was banished into the void. This power vaccuum served to elevate Sauron from servitor to the greatest foe Middle Earth would ever face.
Sauron's career began as an assistant to Aule, a Valar (think Archangel/nature spirit), the Master Smith of these custodians of Middle Earth. Aule would go on to create the Dwarves, while Sauron, trained with the craft of the forge, plotted to overthrow the Valar and rule Middle Earth himself. To do this, he realized he would need to dominate the races of Elves, Dwarves, Men. This was easier said then done. The Elves possessed no ambition to manipulate. Dwarves were stubborn. Men were great, then - and not easily charmed.
After an age of serious thought, Sauron decided to forge a Ring of Power that would dominate these races. His plan was to create rings which granted power to their wearers, but also controlled their minds under Sauron's will. The problem was, despite his tutelage from Aule, Sauron lacked some skills. Skills and knowledge possessed by the wise and immortal Elves.
In those days, Sauron was strong enough to assume pleasing shapes, and one of these - Annatar, Lord of Gifts, became his new face for the first phase of his master plan. He went to Eregion where Galadriel and Celebrimbor lived. Celebrimbor was, arguably, the most skilled of the Elves yet living and his forge created the most amazing works including a forged glass call laen that built the magnificent spires of the Elvish city. Annatar befriended him, crafting things that Celebrimbor had never seen and whispering into his ear that if they combined their skills, they would create beauty unseen in all Middle Earth.
The Elves greatest failing and yet that intrinsic thing that gives them their heart is their obsession with beauty, and Celebrimbor carried a great deal of that obsession. Together, he and Annatar began forging rings of power, even as Galadriel disdained Annatar, never fully trusting him, but with no evidence to prove his identity as Sauron.
First, they forged the Nine Rings for Men. These rings were designed to prolong life, that thing coveted most by Men. Human fear of death would be the lure of these nine bands.
Secondly, they forged the Seven Rings for Dwarves. These were designed simply to dominate the will of the wearers. Their intrinsic beauty would make any Dwarf kill to possess it.
It seems that Celebrimbor was not as much a dupe as you might think. He collaborated with the forging of the rings, obsessed with proving his skill to Annatar, but he seems also not to have fully trusted the Lord of Gifts. In secret, he forged three rings containing the power of nature. Nenya, the ring of water. Narya, the ring of fire, Vilya, the ring of air. Sauron never touched these rings, a fact that would become a life-saver for the Elves later on.
Annatar, having learned everything he needed from Celebrimbor in the forging of the rings, abandoned Eregion and returned to Mount Doom, and in its volcanic fires, he forged the One Ring, linking its powers to all the others and dominating all who wore the other rings. The energy required to achieve this was enormous, draining Sauron's own essence, destroying his beauty.
The instant he put the One Ring on, there were revelations. Celebrimbor instantly realized he'd been deceived. Sauron realized Celebrimbor forged three rings in secret. Sauron swiftly invaded Eregion and siezed the rings of power, but the Three remained out of his reach. In time, they would find masters who used their power to shield the land and the hearts from Sauron's glaring eye.
Nenya, the water ring, would pass to Galadriel, who used its power to weave silver mist through her new kindgom of Lothlorien.
Vilya, the air ring, passed to Elrond, who used it to shield Rivendell.
Narya, the fire ring, passed to Gandalf, making him the Servant of the Secret Fire, and (if you think about it) someone who fought fire with fire when he encounted and eventually defeated the Balrog in Moria.)
Cheated of the Elven rings, Sauron decided he'd destroy the Elves. He gave the Nine Rings to nine kings in the lands of Men. Each wearer immediately fell under Sauron's will. As ages passed, they grew into shadows of themselves, their lives stretched out unnaturally long. They would become the Nazgul, the Ringwraiths.
The Seven he gave to Dwarves, but he's underestimated their stone-hard stubborness, a quality their maker, Aule, specifically built into them to make them more pragmatic. The Seven did not dominate their wearers, but instead awoke a bottomless greed that set the Dwarves to mining too deeply into the Earth.
Sauron made his power play, sending out waves of Orcs, Elves corrupted into monstrous reflections of themselves. A Last Alliance of Men, Elves and Dwarves stood against him at the end of that age. The One Ring was miraculously cut from his finger, destroying his humanlike form, and leaving him able to assume only the shape of a flaming eye. Protected in his dark tower Baradur, he waited for his Ring, which possessed so much of himself, to return to him.
You know the rest of the story if you've read or watched Lord of the Rings. Sauron's plan to dominate Middle Earth end with the destruction of the One Ring and all the essence he'd put into it. This also destroyed the Nine and the Seven, and the Three, still linked to the One, lost their power over time.
In this scene, Annatar leaves the forge where he has made the One Ring, which glitters on his finger. Flushed with power and the desire to capture the Three Rings, his Elven eyes revert back to his own catlike ones, which are kindled with fire. His beauty is evaporating.