With the recent news that Bette Midler will be making an appearance sometime in Season 4 I got to thinking about Glee's best and worst celebrity appearances. Glee gets a lot of grief from a lot of people for its apparent overuse of stunt casting- but I don't think this is entirely fair. Most of the criticisms it gets is that because Glee has a massive cast already, the audience doesn't like when a famous new celebrity is introduced who gets far more screen time than many of their favorite characters. I understand this criticism, but when a celebrity is used on Glee correctly it can really breathe new life into the show. I hear a lot of people these days moaning about the fact that Glee isn't as good as it was in its critically acclaimed Season 1, and one of their arguments is that Glee has become too over reliant on stunt casting as the seasons have gone on. This is bulls**t. Even as early as Episode 3, Josh Groban was introduce into the Glee world playing himself, who visited the town where the Glee characters exist. I am all for celebrities being used as important characters, or characters with a purpose and their own new back-stories, but I do not like when celebrities play over the top and most of the time cruel versions of themselves and are introduced unrealistically into the fictional world. This list explores what I consider to be the 5 greatest Glee celebrity guest stars whose introduction if anything improved the show and the 5 worst celebrity appearances which were either so out of place in the Glee universe, had me rolling my eyes at the television, or most likely both.