Calmacil (King of Gondor)
From Tolkien Gateway
Calmacil was the eighteenth King of Gondor and the brother of Narmacil I whom he succeeded as King in 1294 T.A.
His reign lasted for ten years in which his son Minalcar continued his function as Regent (a function he had held previously during Narmacil's reign). It therefore would seem he never held .(nor, perhaps, desired) any actual power.