Spoilers

Main (favorite) characters who die:

Albus Dumbledore

Sirius Black

Lupin and Tonks

Dobby the House Elf

Fred Weasly

Mad-Eye Moody

Harry Potter (comes back to life)

Severus Snape

''' There was a prophocey by Professor Trelawney that said a boy was to be born who would bring down Lord Voldermort. Longbottom was born the same time as Harry was and couldv'e been the "boy who lived" if the traitor/spy who was evesdropping would have heard the whole prophecy. At the time the spy was Snape. After learning of the plan to kill the Potters, Snape felt guilty (because he loved Lilly Potter) and told Dumbledore and started working with Dumbledore against Voldermort then. '''

''' Snape was in love with Lilly Potter and playing for the good guys the whole time, protecting her son, Harry. He dies by the hands of Voldermort who doesn't know he was betraying Voldermort. '''

13 Years Later:

Ginny and Harry marry. Have kids, Lilly, Albus, and James.

Malfoy has a child and sends him to Hogwarts with Harry's children. (Malfoy and Harry are now on friendly speaking terms)

Ron and Hermionie get married and have children of their own.