[Saurreg]

My choice of greatest elf would have to be Erenion Gil-galad. In the time when his brethens were leaving Middle Earth in droves or were simply keeping to themselves, Gil-galad established the Kingdom of Lindon as a last bastion against Sauron and the dark forces of Mordor. Without his heroic and inspirational leadership, Sauron's legions would have extended all the way to the bays of Belfalas. Also, when Elendil and his sons were casted upon the shores of Middle-Earth as ship-wrecks, had Gil-galad not extended his hand of friendship, it would have been impossible for the exiled Numenoreans to establish their own Kingdoms.

Gil-galad looked through the disguise of the servants of Morder and even that of Annatar himself and realised his intends. Not only did he reject Sauron's advances, he even sent Elrond to persuade the elves of Eregion to reject Sauron too and later to aid in their defence when the Eregionians realized their folly. With the fall of Eregion, I believe he conmissioned Elrond to bulid Rivendell as a hidden refugee for not only the elves of Eregion but for all who are wreary and oppressed. By the time Sauron had created the one ring and enslaved the nine kings of men (and inturn their kingdoms), he was all-powerful. That didn't stop Gil-galad from creating a last alliance to defeat Sauron. Many would have fled before the might of the power-mad maiar but the High King knew that the time had come for the final struggle and did not shy from it. Gil-galad must have known that he would not come out alive from the land of Mordor and it was with this farsightedness that he left Vilya in the custody of Elrond and made him heir and regent.

Gil-galad's story was brief but pivotal. He was a fine example of how one can still bev great even though he had not seen the lights of the two-trees in Valinor. His accomplishments speak for themselves.