Sauron being evil through the ages (em,sorry for my english)
1) The Years of the Lamps - Mairon (future Sauron) is one of Aule’s smiths and Melkor’s spy among ainur first on Almaren,then in Valinor.
2) The Years of the Trees - The Years of the Sun,450-s of the First Age. Sauron-Gorthaur the Cruel is Melkor’s right hand,the most powerful of his servants,
beloved maia (c) wikipedia, sorcerer, shapeshifter, master of ghosts and illusions, lord of Melkor’s Werevolves and commander of Angband. Still beautiful,already have cat-eyes,his hair became more red,as fire and gold - Melkor’s elements.
3) ”True” form, End of the First Age - Second Age,until the downfall of Numenor. After battle on Tol-in-Gaurhoth Sauron was not in favor, and after War of Wrath he lost his master Melkor. He refused to return to Valinor with Eonwe and stayed in Middle Earth. For 600 years he begin to slowly lose his mind. His hair became gray and his beauty fades away.
4) End of the Second Age. Sauron dies during downfall of Numenor. His spirit can’t take a ”fair” form anymore - since this moment his physical form became horrible