Ar-Belzagar (Second Age 2516 – 2825, aged 309 years) was born Calmacil, the son of Tar-Alcarin, King of Númenor. He was a great warrior of his nation, further expanding Númenor's influence in Middle-earth. He was also an ardent member of the King's Men and during his time Númenóreans became increasingly hardened against the will of the Valar.
After the death of his father, Calmacil took up the Sceptre as Tar-Calmacil, a Quenya name like that of his forefathers. His allies, the King's Men, called him Ar-Belzagar, his Quenya name translated to his native Adûnaic tongue. His successors also had Adûnaic names, further showing their disdain for Elves and the Valar.
Both Calmacil and Belzagar mean "Sword of Light", a reference to his warlike youth.