Amandil - The eventual rise of the Kingdoms Gondor and Arnor has its roots in a Númenórean captain named Amandil.  He was the grandfather of Anárion and Isildur, the founders of those kingdoms, and was himself descended from Silmarien, the daughter of Tar-Elendil (see Silmarien).  Therefore, he was of the royal line, but not the ruling one; and in his time was an advisor to the King of Númenor.  However, things changed with the arrival of Sauron.

"Yet there dwelt still a remnant of the Faithful (those still loyal to the Eldar)...chief among them, to whom they looked for leading and courage in evil days, was Amandil, councillor of the King, and his son, Elendil, whose sons were Isildur and Anárion, then young men by the reckoning of Númenor.  Amandil and Elendil were great ship-captains, and they were of the line of Elros Tar-Minyatur, though not of the ruling house to whom belonged the crown and the thrown in the city of Armenelos.  In the days of their youth together Amandil had been dear to Pharazôn, and though he was of the Elf-friends he remained in his council until the coming of Sauron.  Now he was dismissed, for Sauron hated him above all others in Númenor.  But he was so noble, and had been so mighty a captain of the sea, that he was still held in honour by many of the people, and neither the King nor Sauron dared to lay hands on him as yet." ~The Silmarillion (Akallabêth)