Despite repeated denials from show creator J. J. Abrams and showrunners Damon Lindelof and Carlton Cuse, fans have long worried that “Lost” would end with a “they were dead the whole time” twist. However, the final episode “The End” takes pains to explicitly clarify that all the events that took place on the island were actually real.
The first episode of Season 6 perplexed fans by introducing an alternate reality in which Oceanic Flight 815 never crashed and many characters have drastically different roles. “The End” reveals that this alternate reality is actually the afterlife, where all the Oceanic survivors are brought back together following their deaths.
However, this doesn’t mean that all the characters died at the same time — they all died at different times, some way back in season one, and others many years after the end of season six. But time works differently in the afterlife, so to the characters, it feels as though they all arrived simultaneously.
Some “Lost” characters, such as Boone, Shannon, Locke, and Sayid, died throughout seasons one to six, while others like Kate, Bernard, Desmond, and Claire presumably died many years after the finale. Hurley and Ben, who became the new protectors of the island, would likely have outlived the other survivors by a wide margin before eventually dying.
A good portion of the finale focuses on the question of who will fill Jacob's role as the protector of the Heart of the Island, which turns out to be a magical, glowing pool at the island's center. This pool is supposedly the source of all life, death, and rebirth, and according to Jacob, it's the cork holding back a malevolent force that could destroy the world.