Tar-Atanamir (Q. ‘Man-jewel’ or ‘Jewel-of-Men’) was the thirteenth king of Númenor. He was called Atanamir the Great for his wealth and power. Under his rule, Númenor had reached the zenith of its bliss, and his reign is generally considered to have been the beginning of its moral decline.
Cruel to the Men of Middle-earth, Tar-Atanamir was also one of the first to openly oppose the Ban of the Valar, and when an aggrieved Manwë sent messengers to Númenor to soothe the King and explain the Ban, Tar-Atanamir rejected their counsels.
He was the first King to cling to life as he began to age, and refused to give up the Sceptre to his heir until death took him. After his son, Tar-Ancalimon, succeeded him, Númenor split into factions – the King’s Men (those in opposition to the Ban) and the Faithful (those who still revered the Valar) – which ultimately brought about civil war and the eventual Downfall of Númenor.