Who is the most evil demon?

I'm curious, can you elaborate on your thoughts about who you consider to be the most evil demon? Is there a specific mythology or cultural tradition you're drawing from? Are there any characteristics or actions that you believe make this demon stand out as particularly sinister? Additionally, have you given any thought to the moral complexity of labeling any being as "evil," or do you believe there are clear-cut definitions of good and evil in this context? I'd be interested to hear your perspective on this intriguing question.