Jo Harvelle

I'd like to take a moment to remember Jo because I thought she was friggin awesome. Sure she was pretty immature and out of her depth in the beginning, 

but later you could see how much she had grown as a character.

 I know that many people thought of Dean and Jo's relationship as brother/sister, but I do think that Dean really loved Jo or at least had deep feelings for her.

I think that the scene where Dean says goodbye to Jo is one of the most heartbreaking scenes in the entire show. You could see him trying to hold it together when he was telling Bobby the news. It was such a moving moment because they barely said anything, they just shared a look. He had to physically tear himself away from her. Dean even still uses the gun she gave him before she died. I felt like Jo and Dean could have been way more than they were, but we probably will never get to find out.