The Walking Dead is often cited as being one of the most gruesome and dark TV shows currently on air, and while this is true, it's actually quite tame in comparison to its comic counterpart.
Having recently come to an end, The Walking Dead comic series contains one hundred and ninety-three issues (not including one-offs) that don't have to worry about passing different rating boards. Because of this, The Walking Dead comics go into some dark territories.
Nothing is off the table with the comic series. It doesn't matter who you are, you're constantly at risk of a pretty horrific death at anytime. The series really goes out of its way to explore all different types of madness that you would see in a true post apocalyptic America, rarely holding back.
While this is all in service to the story that writer Robert Kirkman wanted to tell, there are still quite a few times where things were taken a bit too far.
Some of these scenes have been translated onto the show, but even then they were toned down. The others were simply too dark or risky to actually put on air. And to be honest, it's probably for best it stays that way.