TV shows and comic books actually have much in common. In both mediums, characters who have died can often come back to life. So when the writers of a show want the audience to understand that a character death will be permanent, they often go a bit overboard with the death to really drive it home. From sci-fi to sitcoms, these TV shows all featured spectacularly cruel character deaths. Done simply to prove that the character was not coming back.
"Cheers"
On "Cheers," the character of Eddie LeBec was Carla's on-again, off-again love interest. The two eventually married, but then Eddie got a particularly ignominious off-screen death when he was run over by a Zamboni and killed. In the same episode, fans also learned that Eddie was a bigamist who had gotten his other wife pregnant.
The reason behind this cruel death (and dark bit of character revelation) was simple: the actor who played Eddie had done a radio interview where he insulted Rhea Perlman, who played Carla. She heard the remark he made, and demanded that he get written off from the show, permanently.
When Rory Cochrane asked to be written out of the show, his character Tim Speedle died a particularly nasty death. The manner of his death seems to indicate the writers were bitter about Cochrane's departure from the series. Tim Speedle was killed when his gun jammed during a shootout.
The odd thing was that just one episode prior, his gun had also jammed, forcing many fans to question why Tim wouldn't have learned his lesson from the previous incident. The writers probably should have just put Tim on a bus, so the actor could return in the future if he changed his mind.
"ER"
Dr. Robert Romano was brash and abrasive, but he was also funny: he was the character every "ER" fan loved to hate. So when he lost his arm after backing into a helicopter's tail rotor in Season 9, fans had some pretty mixed reactions. The arm was reattached, but not fully functional.
In Season 10, Dr. Romano saw a helicopter for the first time since his accident, and had a panic attack. The helicopter was then buffeted by strong winds, came crashing down, and killed Romano. Pratt joked that Romano must have done something awful to a helicopter in a previous life. Fans knew that Romano wouldn't be coming back after that accident, although he actually did reappear for one episode in Season 15.
"L.A. Law"
Who could forget the famous episode where Roz steps into an elevator without looking, only to plummet to her death when the elevator cubicle isn't actually in place? It was a clear way to show viewers that Roz was gone for good, though it took many fans completely by surprise.
Here's kind of a weird one. In the third season "Doctor Who" serial "The Myth Makers," a new character named Katarina sneaks onto the TARDIS, becoming the doctor's newest companion. Most companions stick around for a while, but Katarina was killed off in the very next serial, "The Daleks' Master Plan." In fact, she was the very first "Who" companion to get killed while traveling with the Doctor.
Strangely enough, the very first scene that Adrienne Hill filmed as Katarina was this death scene. In other words, the writers conceived of the character, wrote a few scripts, decided they no longer liked the character, and wrote a new script where she got killed off ... all before the actress had filmed a single scene!

