He’s the main bad guy.
He was born as an elf, but became BAD.
In the Lord of the Rings series, he is an Eye. —————–>
Before he was destroyed, he was a walking figure with no body because the Ring makes you invisible.
Here is his backstory:
He was once an elf just like any other. But he became an apprentice of a dark lord. After his master was killed, he formed an evil plan. He disguised himself as a beautiful elf and convinced an elven black smith to make rings of power. Nine were made for the Men. Seven for the Dwarves. Three for the Elves. While those were being made, Sauron made one of his own in the fires of Mount Doom. It contained ALL of his evil and hatred. It gave you an extra long life and made you invisible when you put it on.
After it was created, he used in battle for Middle-Earth. After he killed Elendil (the king of Arnor and Gondor), his son, Isildur, was so mad and angry, he used it to cut off some of Sauron’s fingers. Along with the one that held the ring. Elrond took him into the volcano, where it was made, and told him to throw it in. But the ring’s power was too strong. Isildur kept it and wore it around his neck. He wore until he was attacked and put it on and ran into a lake. It fell off and he was shot.