Alright, this is the third time Culverton Smith from BBC's Sherlock is being discussed here, so this is probably becoming a pattern, but because there are no rules forbidding re-proposals, I'll just start the discussion.
So as a restatement, Culverton is a serial killer who lures people into his "hospital" before torturing them to death. While torturing them, he would force them to say that they don't want to die just to make the murder more enjoyable for him. Nuff said.
Now, here are the arguments against him, and here's why I find them invalid:
1) Culverton's crimes are offscreen. However, I don't find this disqualifying. We see the bodies of his victims onscreen, and he has an established pattern. Also, while viciously attempting to torture Sherlock to death, he openly explains why he kills people: watching people suffer and die makes him feel happy. So yeah, no. Not disqualifying.
2) Moriarty is more heinous. However, this can easily be justified. Moriarty has higher resources (more screentime, more intelligent, etc.). And even so, Culverton is equally as vicious and sadistic, and from what I remember, he has a high body count. So this isn't disqualifying, either. And finally...
3) Culverton possibly cares about his daughter. Okay, come on, it was implied he wanted to *kill* her. And if anything, his relation with her seems more perverted than genuine. And if we were to use logic, Culverton's blatantly sadistic and disgusting personality tells us all we need to know about him: he's an irredeemable psychopath who is completely devoid of redeeming qualities. The majority of users on this wiki voted to keep Roger despite the possibility that he felt remorse for his actions. They say that since it's unclear whether he felt remorse or not, we keep him. If that's the case, I don't see any reason to give Culverton the "too ambiguous to qualify" treatment.
So ultimately, I'm giving a "yes". Please comment.