You could mean Sauron, who is a Maia spirit, and servant to Morgoth, who turned Sauron from a Balrog into humanoid in an attempt to destroy all of mankind. Or you could mean Morgoth himself, who is a valar spirit, and the greatest evil force in the LOTR universe, directly responsible for all evil creatures in middle earth, and fully accountable for every innocent death in LOTR history.
Treebeard
The name of the Lord of the rings is Sauron. This is because he was the one that made the one ring that bound them, he made the most powerful ring that was lord to the others. And because he kept this ring for himself this meant he became the lord of the Rings.
Gollum
Priceless.
The name of the Eagle that rescued Gandalf from the tower of Orthanc in Isengard is 'Gwaihir the Windlord, swiftest of the Great Eagles' Around page 340 in Fellowship of the Ring, chapter Council of Elrond.
The Fellowship of the Ring
The Lord of the Ring is Sauron, there is no other Lord. But the first ring bearer that was not Sauron was Isildur. The first Lord of the Rings book and movie is 'The Fellowship of the Ring.'
Treebeard
The name "Lord of the Flies" is a literal translation of the name of the biblical name Beelzebub, a powerful demon in hell sometimes thought to be the devil himself.
Satan (with a long A at the front) or the Hell's Lord
The Two Towers
It was homage to the beast and this, being the Lord of the Flies later, is related to the devil. Lord of the flies in Hebrew has a similar name to Beelzebub, which is the devil. It signifies that the devil is all part of us, when he says he is part of them to Simon during one of his seizures.
Gandalf
The elves
Mt. Doom
The name of the Lord of the rings is Sauron. This is because he was the one that made the one ring that bound them, he made the most powerful ring that was lord to the others. And because he kept this ring for himself this meant he became the lord of the Rings.
A little. Lord Voldemort possessed characters and animals in the series and it is believed that the Devil possesses people.