When an actor leaves a hit show, it can either be a blessing or a curse. Sometimes, write-outs are worked into a show very nicely, like with the revolving door on Grey's Anatomy that only adds to the drama factor. In other cases, though, a character is so essential that their disappearance downright dooms the series — especially when they're replaced by someone who doesn't have the same appeal as the original star. Here are a few TV shows that just couldn't recover from the loss and replacement of a major cast member...