We've all heard that old adage that history repeats itself, and it all goes the same in the wizarding world.
You may also know the tale of the three Peverell brothers, who evaded Death and who were granted gifts (the wand, the Resurrection Stone, and an invisibility cloak) by Death for being oh-so-clever. In case you need a refresher, check out the animated story below narrated by Hermione:
According to this Harry Potter theorist, he supposes the deathly hallows to have come into wizards' hands again, repeating the famous fable from so long ago. Perhaps Dumbledore is death for Voldemort, Snape, and Harry.
Severus Snape had been in love with Lily Potter, and even after her untimely death, everything he did was in vain of her name.
He represents the brother with the Resurrection Stone, who is stuck on his feelings and the past due to his immense love for LIly.
Lord Voldemort has had dreams of being the most powerful wizard since his start at Hogwarts. He would love nothing more than to own the Elder Wand, the most powerful want of wizard existence.
Harry Potter has evaded death since the cursed night Voldemort killed his parents. He represents the brother with the invisibility cloak who has been hiding and escaping from dying with each obstacle he is faced with.
Harry actually had an invisibility cloak that was passed down from his father James Potter. Harry received this cloak from none other than, you guess it:
Dumbledore was not only behind both Voldemort's and Snape's deaths, he was also the one to greet Harry at King's Cross when he died, which refers to Harry greeting Death like and "old friend," much like the brother in the Peverell fable.
He was also in possession of all three items of the deathly Hallows at once, handing them out much like Death did in the story.
I suppose we will never really know if this is the case or not, but the theory holds up surprisingly well.
Albus Dumbledore is a master wizard, with many secrets and knowledge of some of the most advanced magic. Perhaps he's even older than we thought he is. Perhaps Dumbledore never fully dies, but is a powerful wizard who cycles throughout history in various ways.