5. Will Schuester (Glee)
It's odd to remember that Glee's Will Schuester used to be a central character to the show, which has drastically changed since season 2. Many of the A plot stories surrounded Will's relationship with his crazy wife (later ex-wife) and his pining after Jayma Mays, which no one can blame him for. Eventually, the writers stopped coming up with ways to make his stories interesting. With the exception of a few minor plots in Season 3 and a terrible love triangle with Finn in Season 4 (that he was mostly absent for), Will has become a secondary character with fewer lines than Sue Sylvester (probably). I'm not saying this was for the worst. Will's backing away from the spotlight was welcome, mostly because his character's odd rants and bizarrely close relationship with his students (that the show loves to poke fun at) made him a real stick in the mud. Many, like me, were pleased to see Finn, Kurt and Blaine step up as the show's central leading men.