Elixir of Life
From UnknowableWiki
The Elixir of Life is a draught that can be made with the use of the Philosopher's Stone (PS13). It grants the drinker an extended lifespan, provided that he or she drinks it regularly (PS17).
Nicolas and Perenelle Flamel
Nicolas Flamel is the only known maker of the Philosopher's Stone. He and his wife Perenelle produce large amounts of Elixir of Life, and drink it in order to live for many centuries (PS13).
When Lord Voldemort orchestrates several failed attempts to get to the Stone, the Flamels talk to Albus Dumbledore and decide that it is time for them to die. The Stone is destroyed, and the couple uses what little Elixir they have left to settle their businesses before passing away (PS17). They die some time later (JKRW).
Lord Voldemort
After Lord Voldemort's failed attempt to kill one-year-old Harry Potter, the Dark Lord is reduced to a weak, ghost-like form; he survives only because he made several Horcruxes, and he wills himself to live every day (GF33, HBP23). This cursed life is prolonged when Voldemort gains access to unicorn blood from the Forbidden Forest herd (PS15).
Wishing to strengthen himself, Voldemort plans to obtain the Philosopher's Stone and to fabricate the Elixir of Life, which will render him immortal. His plot fails; Harry Potter's intervention causes Quirinus Quirrell (the professor Voldemort manipulated to get to the Stone) to die, and the Dark Lord has to flee once more (PS17). He eventually decides that regaining his former strength is worthy enough a goal--which he accomplishes with the use of a Dark potion--abandoning the plan of obtaining the Elixir of Life (GF32, GF33).
Albus Dumbledore later explains to Harry Potter that the Elixir of Life is an undesirable solution in Lord Voldemort's point of view, because it would force him to depend entirely on something other than himself to guarantee his survival (HBP23).

