Tar-Calmacil (Second Age 2516 – 2825, aged 299) was the 18th ruler of Númenor, ruling 88 years, from 2737 to 2825. He succeeded his father, Tar-Alcarin, as King. His name means "Bright Sword", which he took in recognition of the territorial victories he had in Middle-earth as a renowned captain of Númenor.
There is a discrepancy in Tolkien's writings as to Tar-Calmacil's successor: Tar-Ardamin, his son, or Ar-Adûnakhôr, his grandson. Specifically, in Appendix A of The Lord of the Rings, Ar-Adûnakhôr is listed as his successor, but in the more expanded "Line of Elros: Kings of Númenor" from Unfinished Tales, he is succeeded by Tar-Ardamin.