Michael Richards Syndrome

A condition when a celebrity becomes so famous for playing one role, song, character, media, etc... that when they try to move to something different, it goes horrible wrong or fails immediately. Or in visual media, when a celebrity plays characters on different shows that are different in name, but the same in personality and demeanor. Can vary in degrees, from minor to very severe. They are usually not flexible when it comes to their performance.
AKA: Michael Richards Disease/Disorder

"Ed O'Neill has Michael Richards Syndrome in that he will always be Al Bundy, but it is a minor case because can still play some other decent characters"

"Joe Pesci has always plays the same character in everything he is in: a easily angered short person, he has Michael Richards Syndrome"