The meaning of all the deaths in HP:

• James and Lily:

  To establish the story line as well as to show orphans of war.

• Cedric Diggory:

  To show Voldemort's mercilessness.

• Sirius Black:

  To show Harry's lack of guidance/parental figures.

• Albus Dumbledore:

  To show the death of a great leader can't stop a war.

• Hedwig:

  To show the end of Harry's childhood.

• Mad Eye:

  To show the death of a solider.

• Dobby:

  To show even the smallest of creatures can die a Hero's death.

• Fred Weasley:

  To show that some deaths you just can't get over. And that's okay.

• Tonks and Remus Lupin:

  To reestablish orphans of war.

• Colin Creevey:

  To show that the good die young, even when they aren't supposed to.

• Severus Snape:

  To show that you can always change your ways. Always.