While Sauron's most notable form in The Lord of the Rings was the Great Eye that hovered over Barad-dûr, his most noteworthy appearance came during the dramatic introduction to The Fellowship of the Ring. The intro depicted the War of the Last Alliance as Men and Elves warred with Sauron's forces on the planes of Mordor. When defeat seemed imminent, Sauron emerged from his tower to do battle, wearing a terrifying set of armor. Wielding a great mace, he was indomitable, until he met his match in Elendil the Tall and the High Elven King Gil-galad. Together, they cast the Dark Lord down and -- at least temporarily -- ended his reign of terror.
Source：https://www.cbr.com/lord-of-rings-what-sauron-really-looks-like/
