A Horcrux is a device that is created and used by the darkest of Dark witches and wizards, those seeking immortality. Within a Horcrux, one conceals part of the soul to prevent death. In order to do so, the soul must be torn into two pieces: one for the Horcrux, and one that remains in the physical body. To create a Horcrux, one must commit "the supreme act of evil" — murder, which "rips the soul apart." They must then perform a special spell (the incantation of which has not been revealed) which will harness their soul, allowing them to place it into an object at will.
The act of creating a Horcrux is considered to be dangerously unnatural. In one of Professor Horace Slughorn's memories (captured in Albus Dumbledore's Pensieve), Tom Riddle (the young Lord Voldemort) asks Slughorn what a Horcrux is and how it is created. Slughorn tells him that "the soul is supposed to remain intact and whole...splitting it is an act against nature."
While there do not appear to be any specific stipulations about the nature of the items that become Horcruxes, wizards commonly choose items of either sentimental or monetary value (or both) to serve the purpose, in order to prevent accidental destruction.
While a piece of a wizard's soul exists in the Horcrux, he or she cannot be killed. This is how Lord Voldemort escaped death when his killing curse rebounded during his fateful attack on Harry Potter. However, when somebody in possession of a Horcrux is 'killed', they are reduced to a painful half-life, less than a ghost. Professor Slughorn warned Riddle that few wizards would want it, as it is arguably worse than death.
Possible Horcruxes
Voldemort is believed to have created six Horcruxes, thus rending his soul into seven pieces (the last piece stayed with his body). Albus Dumbledore suspected that the items that were Voldemort's Horcruxes were:
- Marvolo Gaunt's ring, hidden in Gaunt's shack (this Horcrux was destroyed by Dumbledore before the start of the school year in Harry Potter and the Half-Blood Prince, though the ring physically survives with its black stone now 'cracked down the middle') Tom Riddle's diary (destroyed by Harry in Harry Potter and the Chamber of Secrets) A locket once belonging to Salazar Slytherin, hidden in an underwater cave. This Horcrux was not recovered as it was replaced with a fake by an unidentified R.A.B., and it is not clear if it was destroyed. A cup once belonging to Helga Hufflepuff Either:
- An unknown item belonging to Rowena Ravenclaw.
- The great snake Nagini (once Voldemort was unable to procure an item belonging to Gryffindor) (probably created in murdering Frank Bryce, an old groundskeeper living in Voldemort's father's garden hut)
- An unknown item belonging to Godric Gryffindor (Dumbledore indicates that Gryffindor's last surviving possession, his sword, is accounted for; it resides in a glass case in his office, though he overlooks the Sorting Hat in this enumeration), or
All of his Horcruxes have a special meaning to Voldemort, whether it be from a founder of Hogwarts where he felt most at home, or from a trophy of his torturous actions.
Voldemort and Harry
Dumbledore believed the final Horcrux was to be made from Harry Potter's murder, considering his importance as the "Chosen One" foretold by Sibyll Trelawney's prophecy. Because Voldemort did not succeed in killing Harry, he was unable to use him to create the last Horcrux. Dumbledore thought that the murder of Frank Bryce was used instead, and that Nagini was the vessel.
Dumbledore believes that Voldemort made six Horcruxes after viewing a memory belonging to Slughorn. In this memory Tom Riddle tells Slughorn that he believes having one's soul split into seven parts would make one stronger, because seven is the most powerful magical number.
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