[@Pirouette]A woobie is a character you feel sorry for. That you want to hug. Examples would be the Elric brothers from FMA (They lost their mother and most of their bodies at a young age and only survived by their alchemist knowledge), Peter Parker (His orgin story revolves around letting his greed and pettyness keeping him from stopping the man that would kill Uncle Ben), and Samurai Jack (His home was conquered at  young age and he has spent his life toiling to stop Aku). 

You'll notice a lot of these are related toa  tragic backstory. TV Tropes can list many other examples to.