Dumbledore suspects Voldemort of splitting his soul into seven parts because this is the most magical number. One part is inside his regenerated body and the others are Horcruxes.

Horcruxes:

• Tom Riddle's Diary (destroyed)
• Marvolo's Ring (destroyed)
• The locket (possibly destoroyed by R.A.B)
• Hufflepuff's Cup (not confirmed)
• An object belonging to Rowena Ravenclaw (not confirmed)
• Nagini the snake (not confirmed)

Dumbledore also suspects that Voldemort had only five Horcruxes when he entered the house of Lily and James Potter and intended to create his final Horcrux by killing Harry; an act which he believed would give him invincibility.

Theories

Was the reason Snape killed Dumbledore because he knew that Dumbledore was one of Voldemort's horcruxes and would therefore ultimately have to die in order for Harry to succeed in klling Voldemort?

A horcrux resides in Vernon Dursley

In the opening chapter of "Order of the Phoenix," Harry suffers a severe pain in his head when his Uncle Vernon touches him. His uncle feels such severe pain on contact with Harry at this time that he is forced to release him.

This incident bears a significance resemblance to the climax of "Philosopher's Stone" where Quirell was unable to force the stone from Harry as they both experienced considerable pain when they made contact.

The other similarity is that the degree of pain experienced by the person attempting to control Harry seems to be in direct proportion to the degree of head pain Harry feels.

Is the pain Vernon Dursley experiences in this incident merely as a result of an automatic magical reflex on Harry's part (similar to the incident with the vanishing glass at the zoo in "Philosopher's Stone") or is it an indication of somthing much more complicated?

Is it perhaps an indication that Vernon is strongly involved with either Voldermort's or Dumbledore's side (Harry had a desire to bite Dumbledore in "Order of the Phoenix" because of the nature of his connection with Voldemort)? Is he perhaps under the Imperius Curse?

Or perhaps Mr. Dursley, unknowingly, contains one of Voldemort's seven horcruxes?

Is this incident of vital importance to Harry's quest to destroy Voldemort in the final battle?

Dementor's Kiss

Harry will receive a Dementor's kiss and it will seem to everyone as though he is gone but in actual fact it will have been Voldemort's soul that got sucked out of him, not his own, so he will be fine ... and can go along and kill Voldemort (possibly minus a scar).

Reasons for this:

Dementor's Kiss has to have a use in the books, it really is a rather elaborate way of killing someone, why not just have them suck out your life? The soul-sucking bit has to be rather important somewhere. thanks to wizardess from TLC

Horcruxes heavily involve Potions

PS: 8-102

Creating a horcrux requires potion. Evidence:

Snape says he can teach you "how to put a stopper in death." The only known way of preventing death is by creating a horcrux/horcruxes. However, Snape may have been referring to a poison.

Snape would not say he could teach them how to put a stopper in death if it was not potions-related. Therefore, if he was referering to Horcruxes, they must involve at least one potion.

Tom Riddle (Voldemort as a boy) asked Slughorn, the potions teacher, about Horcruxes. It is not clear how many people in the wizarding world know what a horcrux is, but it may be assumed that very few do due to its getting only one mention in all the book in the library. But Slughorn knew because he was a potions teacher. However, Tom choosing to ask Slughorn this above all anyone else may have been only because Slughorn showed a particular fondness for him.

Voldemort's known Horcruxes are able to contain potions. The ring may have only been stone covered with a potion within. The part of the necklace which contained the note R.A.B. may have contained potion in the real Horcrux. The diary very possibly was soaked in potion. Perhaps, for that reason, when Harry drove the fang into the diary, it was potion as well as ink which flowed out.

Destroying Horcruxes is Fatal

In all three instances where an attempt has been made to either find or destroy a Horcrux, the people involved have been seriously injured.

Example 1: The Diary - Harry would have been killed by the poison of the Basilisk had Fawkes not arrived and cried to heal the wound.

Example 2: Slytherin's Ring - When he destroyed this, Dumbledore received a black, shrivelled and almost useless arm.

Example 3: The necklace - Although fake, the journey of Harry and Dumbledore to reach it was exceedingly dangerous and may have resulted in the death of one or both.

There are probably five Horcruxes left to find. If each inflicts the same degree of injury on Harry as the ring to Dumbledore, he will be so weak by the time he has destroyed them all that he will be both physically and mentally unable to damage Voldemort in any way when the final confrontation arrives. Failing this, he will will be killed on his quest to find one of the Horcruxes.

How is the soul ripped?

When the soul is torn apart to create a Horcrux, it is not specified in the books whether it is ripped in half or in "chunks." If it was ripped in half each time then the different bits of the soul would be different sizes. It would therefore make sense that as the part of the soul decreased in size the size of the injury would also decrease. Assuming this theory is correct, if the ring was the first Horcrux made, which is likely since it is the object most closely related to Voldemort, then it would inflict the greatest injury. In this case, Harry will be less badly injured than would first be suspected and will have a greatest chance in the final confrontattion with Voldemort. Thanks to *Lu* from TLC.

Voldemort does not know when a Horcrux is destroyed

The note left by R.A.B. gives the impression of intending to surprise Voldemort. R.A.B. obviously knew about Voldemort's Horcruxes and if he/she thinks that Voldemort does not know and cannot feel when one of his Horcruxes is destroyed, it is probably correct. Dumbledore thinks that too little human remains in Voldemort for him to feel when a part of his soul has been destroyed.

The "fake" horcrux is actually a real Horcrux

Everybody thinks that the necklace is a fake, swapped while the real Horcrux has been taken by R.A.B. What if this is the real Horcrux and nobody but Voldemort has ever touched it? Perhaps Voldemort put the note there as an added percaution, thinking that if it was thought to be a fake, the necklace was much less likely to be destroyed.

Harry is a horcrux

Dumbledore said it was risky to have living things as horcruxes, but possible.

Perhaps Voldemort heard the prophecy and believed that either he or Harry must die in the end.

In this case, perhaps he transfered part of his soul into Harry, knowing that, if he killed Harry, although disposing of a part of his own soul, he would continue to live due to having previously created a total of six horcruxes.

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