John Locke stands out as one of the 815 survivors who, despite his flaws, is an important member of the "society" formed after the crash. Especially after miraculously regaining the use of his legs, he starts his personal journey to fulfill his destiny, to move from a person who was "lost" to a person who is "found". He helps Jack to deal with his role as a leader, Charlie to overcome his addictions, Shannon to get over her relationship with Boone, Michael to realize how special Walt is etc. Even if he shows extremely gullible in season 2, first with the button - which, however, proved to be real - and then with "Henry Gale", and after all that he is driven by his nihilism to destroy the computer, he later regains his initial optimism and stands up as a key-player on the island. His hunting insticts and his loyalty to what needs to be done are his best qualities, and his death was one ultimate sacrifice to serve a greater purpose. Season 5 revealed eventually that after Ajira 316 crashed another person emerged, who looked like Locke, but was in many ways "darker". And eventually it was proved that it was an impostor - at least that's what Jacob said to Ben. So, what would that mean for the real John Locke? "Dead IS dead"? No matter what, I will always remember John Locke as a central figure in "Lost".