Think of some of the most popular TV shows these days – "Game of Thrones," "The Walking Dead," "Sons of Anarchy," "Boardwalk Empire," "True Blood." While wildly different in many ways, they have one thing in common: Mayhem.  

All that violence takes a toll on the cast of characters.  They're murdered, die in battle, are fatally attacked by zombies.  Sometimes the victims are marginal to the story. Sometimes they are main characters, often beloved by the audience.

So, why do the writers kill Opie on "Sons of Anarchy," or Hershel Greene on "The Walking Dead"?

Writer Eric Overmyer has worked on shows where there were a lot of fatalities, including "Law and Order," "The Wire" and "Boardwalk Empire." He says in programs where violence is a rich part of the story, people simply have to die. As for the death of main characters, sometimes there is, as Overmyer puts it, a narrative imperative. The story demands that the character die.

Or sometimes, the writers just don't know what else to do. That may have been the case with the character Opie, played by Ryan Hurst on the FX series, "Sons of Anarchy."

Over the course of five seasons, Opie had been sent to prison and was freed, only to see his wife killed. Later his father was murdered by one of his fellow gang members. Opie ended up back behind bars. Says the show's creator and head writer, Kurt Sutter, " I just felt there were not a lot of places we could go after we'd damaged him so badly."

So Opie died. The writers killed him. They had him beaten to death with a pipe in a brutal prison fight.

Kurt Sutter had to break the bad news to the young actor.

"It's like telling a family member that someone close to them is dead," says Sutter.

The cast held a funeral of sorts for Hurst, taking turns shaving off the long beard he'd grown over his time on the show. It was an emotional moment, with no shortage of tears.

Scott Wilson had a similar experience. He played the beloved character Hershel Greene on AMC's "The Walking Dead." Wilson says everyone on the cast was a little uneasy about their job security.

"There was no way of knowing for sure," says Wilson, "but you did know you were likely to go at any time."

One day, Wilson got called in for a chat with the lead writer, and was told he was to lose his head to the sword of a megalomaniacal rival. On the day he shot the final scene, the entire cast and crew conspired to show their respect and support.

"I came up the set, and everyone was wearing suspenders," Wilson says, noting his character, Hershel, always wore suspenders. "They were all applauding, and it was really quite touching."

Afterwards there was a "death dinner" for Wilson, where everyone celebrated the character's life, and demise. It was almost like attending your own wake, something none of us get in real life. 

That, and the whole process of dying on TV, made a lasting impression on Scott Wilson.

"Because, in a way, I'll never get that kind of recognition when I actually go."