I can't help recalling Firefly, where (spoilers) only the worst, most sadistic bad guy (Adelai Niska) tortures people[1]. He does so using any method he can, not to get information but just because he loves to do it. It is obviously also a warning to other people not to annoy him, but this is almost a secondary purpose, at best equal with causing immense pain to his enemies.
This is a reasonably accurate depiction of torture, as far as I understand the science of it, and it's one of the few reasons torture might actually be used (i.e. at the orders of a complete psychopath.) - although Mal Reynolds seems unfeasibly good at resisting it (any evidence that this occasionally happens? I'd be interested to hear.)
Killing people is not the same as torture, and is not serving the same purpose.
The Firefly gang fight and kill all the time, the first episode forces a pacifist (Book) to confront his objections to violence in a nontrivial moral situation. What they don't do routinely as a tactic is torture people.
A better counterexample would be Jayne and the fed: "Damn, and I was gonna get me a ear, too..."
Mind, the protagonists kill plenty and kill violently in that series, but they're outlaws. Literary convention allows them to do something morally ambiguous.
This is a reasonably accurate depiction of torture, as far as I understand the science of it, and it's one of the few reasons torture might actually be used (i.e. at the orders of a complete psychopath.) - although Mal Reynolds seems unfeasibly good at resisting it (any evidence that this occasionally happens? I'd be interested to hear.)
[1] You can read about the character here: http://firefly.wikia.com/wiki/Adelai_Niska and you can buy the DVD of the original series here: http://www.amazon.co.uk/Firefly-The-Complete-Series-DVD/dp/B... (check out, in similar items, the film Serenity, which rounds off the plotlines from the series nicely.)