Richard Alpert

From Lostpedia, "Richard Alpert (also known as Richardus and by his birth name Ricardo) was a long-time inhabitant of the Island, having arrived in 1867 as a slave on the Black Rock, an slave ship that was washed onto the island. Soon after he arrived, he asked Jacob to make him ageless, and in exchange for this held a leadership position with the Others as an advisor and the sole intermediary between Jacob and the people who were brought to the Island, including Ben and Charles Widmore. Richard believed that even though he could not kill himself, others were capable of killing him. He perpetually appeared to be in his late 30s or early 40s, whether on or off the Island."