For an actor, being a main character on a long-running network television show is, if nothing else, a fantastically lucrative situation. These series tend to pay very well, which is a godsend for serious actors who would love to have the freedom to take roles in indie films (or perhaps work in theater) without having to fret over their finances. Those who are fortunate enough to get cast on such a show can feel a tremendous sense of security -- though they are always aware that while the series will go on, it might not necessarily need to go on with their character.

Getting written out of a successful show can be a rough turn of events for an actor, especially if they're an up-and-comer (like Eric Millegan was when his character Zack Addy was killed off on "Bones"). And it's a decision the producers and writers don't make lightly...