Because Voldemort wanted so. (And Dumbledore wanted so, too; both of them thought Snape was their man but he was really loyal to Dumbledore's .)
Minerva McGonagall becomes Headmistress after Snape is killed by Voldemort.
Severus Snape
Severus Snape, appointed by Voldemort (or his puppet Minister Thickness).
at the end of the book meaniing after the battle of Hogwarts, the headmistress would be Minerva McGonagall __________________________________________________________________ Okay but then who is the deputy??
In New York City you go to this Broadway place and he signs autographs but nothing harry potter. i met him and dan radcliffe there
Severus Snape is named the new Hogwarts Headmaster. He continues to pretend to be on Voldemort's side and is always consulting Dumbledore's portrait, he suggests the idea of the seven Potters to Mundugus and only tells part of the plan to Voldemort. He also gives Harry the sword so he can destroy the Horcruxes. Voldemort thought that because Severus killed Voldemort, that Severus was the owner of the Elder wand so he has Nagini (his snake) kill him. As Snape is dying he gives Harry's his memories which helps to fill in the gaps of the story.
Harry Potter's headmaster is Professor Albus Percival Wulfric Brian Dumbledore
if you really want to know, read this Hedwig Fred Weasley Severous Snape Remus Lupin Nymphadora Tonks many more...
Snape refers to Harry as Hogwarts new celebrity. He then goes on to drill Harry about important Potions knowledge that Harry doesn't know.
Harry Potter and the Deathly Hallows
Most likely every year at hogwart in harry there always always a new teacher in all harry potter except the first harry potter
The lastest (and last) Harry Potter book is Harry Potter and the Deathly Hallows. It was published in 2007.