Gandalf was originally named Olórin, the wisest of the Maiar. He served the Valar and learned from Nienna, who taught patience. He was sent to Middle-earth as one of the Istari to combat Sauron
Orcs were created by Morgoth during the First Age. They were initially deformed Avari and twisted into Orcs. Surviving Orcs settled in Angband's underground fortress. They spread through northern Middle-earth after the Battle of the Powers
Palantírs are indestructible crystal balls from The Lord of the Rings. Made by Elves of Valinor in First Age, possibly by Fëanor. Eight stones total, seven saved by Elendil. Four stones in Gondor, three in Arnor
Sauron has appeared in various forms since creation. He can transform into angel, wolf, serpent, monster, vampire, and Necromancer. By Second Age, he lost his body twice and became increasingly humanoid
Sauron created the Eye after the Downfall of Númenor. The Eye was projected as Sauron's mental image showing unceasing vigilance. It was displayed as an emblem on Orcs' weapons and used as a symbol
Melkor was the most powerful Ainur created by Ilúvatar. He disrupted the Music of the Ainur and defied Ilúvatar's will. Melkor entered Arda with the other Valar, claiming to be master