Not to be repetitive, but I have to go with Snape. Once you hear his entire back story and find out why he was doing everything and his true feelings, it was heart breaking. He never got the one he wanted, and in the end, even though it was hard, he always made sure to protect Lily's son.
Snape, it was really sad that he did all of that to just die.
Fred too, I almost died crying over that one. Gotta agree with Flora_Nightshade, they should have killed Percy instead. Then again, it wouldn't have as much of an impact..
They're all so distinctively sad in their own ways! But as I was reading Dobby definitely hit me the hardest... I mean.. I was BAWLING.
I don't know why when I read it Fred didn't get to me as much... I think it was because of the battle scenario, you know I wasn't really allowed time to grieve or anything...