In the fictional world of J.R.R. Tolkien's Middle-earth, elves have an extremely long lifespan. In The Lord of the Rings, elves are immortal, meaning they do not age and do not die of natural causes. However, elves are not invulnerable and can be killed by injury or disease. In addition, some elves can choose to leave Middle-earth and travel to the Undying Lands, where they can live an even longer existence.