In #StarTrek #TOS episode, "Day of the Dove", Kirk tells Kang to "go to the devil". I guess they couldn't say "hell" on primetime television in the 60s.
In any case, Kang replies, "We have no devil, Kirk."
Of course, eventually they introduce a devil-like figure to Klingon mythology: Fek'Ihr. He torments the souls of the dishonorable in the afterlife.
It's interesting to think that, despite the similarities, maybe Kang didn't see Fek'Ihr as being an actual corollary to the Christian version of Satan. To Klingons, there is no sin: no wicked and righteous. In fact, the first two Klingons created by the gods killed the very gods who created them.
So, to Klingons, wickedness has no meaning. Only honor and dishonor are important.
Caption
Close-up of Klingon mythological figure, Fek'Ihr. He appears as a feral Klingon, hair in disarray, ridges overy most of his face (rather than just his forehead), fangs beared