Professor Longbottom was supposed to kill Nagini, Voldemort's snake. Nagini has to die before Voldemort could die. That's it! ... We destroyed Cedric, he killed Neville, Voldemort won the battle.

What happened to Neville Longbottom?

We now know that Neville ended up marrying Hannah Abbott and became Herbology Professor at Hogwarts. Plus he and his wife lived above the Leaky Cauldron. Neville finally got his happy ending – and here's why he deserved it more than anybody else.

Does Neville Longbottom die in the cursed child?

Neville's death at the hand (or wand) of Cedric means Nagini doesn't die, which somehow leads to Harry dying and Voldemort winning the Battle of Hogwarts.