His death was foreshadowed in Harry Potter and the Prisoner of Azkaban

While enjoying Christmas dinner in the third book, Professor Trelawney freaked out because she believed that, should she join the table, it would mean 13 people would be seated and so the first person to stand would be the first to die. What she didn’t realise was that there were already 13 witches and wizards sat at the table, if you included Peter Pettigrew in Ron’s pocket…

Dumbledore stood up to greet Trelawney, therefore making him the first of the 13 to get up from dinner. Sure, it could be a coincidence, or it could have been a nod about Dumbledore’s fate from J.K. Rowling. Clever!

Dumbledore, at one point, possessed all three Deathly Hallows

From Dumbledore’s letters to Grindelwald in Deathly Hallows, it is obvious that the headmaster of Hogwarts was obsessed with the idea of the Hallows in his youth. It seems fitting then that he should become the only character besides Harry to have owned all three at some point in his life. After winning the Elder Wand in his famous duel with Grindelwald, he came into possession of James Potter’s cloak after borrowing it to study, and kept it safe to give to Harry when he was old enough, meaning that it was in his possession for about a decade. He also came to own the Resurrection Stone, though it came with terrible consequences when he attempted to wield its power and fatally cursed himself.

‘Why,’ said Snape, without preamble, ‘why did you put on that ring? It carries a curse, surely you realised that. Why even touch it?’

Marvolo Gaunt’s ring lay on the desk before Dumbledore. It was cracked; the sword of Gryffindor lay beside it.

Dumbledore grimaced.

‘I … was a fool. Sorely tempted …’

‘Tempted by what?’

Dumbledore did not answer.

Harry Potter and the Deathly Hallows

He can be rather detached

Although the Dumbledore we know and love is always there to help with a twinkle in his eye, J.K. Rowling has admitted that Albus can be a little, well, cold. Back in 2005, she said: ‘I see him as isolated, and a few people have said to me, rightly I think, that he is detached. My sister said to me in a moment of frustration – it was when Hagrid was shut up in his house after Rita Skeeter had published that he was a half-breed – and my sister said to me, “Why didn't Dumbledore go down earlier?”… I said he really had to let Hagrid stew for a while and see if he was going to come out of this on his own, because if he had come out on his own he really would have been better.’