system
Given the following post, respond as if you're commenting on Reddit:
human
[Highlander] How much of the head must be cut off to be considered a kill?

The question that got me thinking of it: If Nearly Headless Nick from Harry Potter was an immortal, would he still have died from the executioner's axe?
gpt
Think of it like the achiles heel.  They are immortal and heal any injuries except those to the neck.  We actually see an immortal with a thick neck scar from a close call centuries ago that never healed.  So yes, Nick would be dead since such a neck injury would definitely kill a human.