Horcrux

A Horcrux is an object in which a wizard stores part of his soul to protect himself from death; making one requires murder, which "rips the soul apart", and it is considered the darkest magic. As long as a Horcrux survives, its maker cannot fully die. Voldemort made several, including a ring that was also the Resurrection Stone and a locket. Horcruxes can be destroyed only by powerful means such as basilisk venom, the Sword of Gryffindor or Fiendfyre.