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.

Meaning of this post:

To make anyone who reads it want to crawl in a hole and drown in their tears.