For the purposes of this question, an "immortal" is a human with powerful regeneration abilities, similar to Logan/Wolverine from X-Men. This immortal can regrow limbs when they are cut off.

I was wondering, if their head is cut off, would it regrow like hydra or would a new body grow from the separated head since it is where the conscious lies? Which case seems most probable and why?

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    $\begingroup$ Welcome to the sit, bob. This seems like a question for the creator of this magical ability, rather than a community of people who will each have a different take on how a given magical ability would function. $\endgroup$
    – Frostfyre
    Commented Aug 1, 2018 at 12:19
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    $\begingroup$ Welcome to WorldBuilding.SE! As Frostfyre noted, this is probably something you'll have to decide for yourself, I'm afraid. You're the one who invented this character's regeneration powers, it's up to you to decide how they work. $\endgroup$
    – F1Krazy
    Commented Aug 1, 2018 at 12:21
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    $\begingroup$ It's super important to know how/why anything regrows to answer that. Also consider option 3 (which to me sounds the most logical, but it's a horrible idea for a story): Both happens. You get two people that way. Also note that the central nervous system isn't just located in the head. "consciousness", well, don't know what that is, but I think many wouldn't really disagree if I stated that what makes you you is not really a strictly located thing, even though there is no doubt the biggest and most important part is in the head $\endgroup$
    – Raditz_35
    Commented Aug 1, 2018 at 12:21
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    $\begingroup$ See: worldbuilding.stackexchange.com/questions/118827/… $\endgroup$
    – Separatrix
    Commented Aug 1, 2018 at 12:39
  • $\begingroup$ If the answer to the question is, "It's the part with the brain that regrows," you should also answer the question, "What happens if the brain is cut perfectly in half?" One solution is that the immortal's soul gets to decide. (Or maybe it's just a coin toss.) $\endgroup$ Commented Aug 1, 2018 at 13:38

2 Answers 2


I can answer the last question assuming that the ability has a basis in biological functions, which the example you have used does, (usually):

The body growing a new head is more probable because it has the reserves of biological material and energy to undertake such a task, a head regrowing a body is less likely in this regard.

However I find it problematic that the body manages to keep functioning without a brain sending impulses to the vital organs like the heart.


Simply put, in current terms this has happened in a few super hero/science fiction moveis and TV, shows such as Highlander, Torchwood, Deadpool 2 etc. and its ruling seems to vary dependent on plot.

In Torchwood, after the immortal character, Captain Jack Harkness, is blown up, he regrew from whichever part was the largest. So in a beheading situation that would be the body, if all limbs and head were removed it would still be the torso as the largest part. this is fine for the show as its not that deep on the science part of science fiction, but my issue is how does the charactter, once regrown, have any memories? if the brain regrew then it should be a blank slate

Then there are cases such as Deadpool, where the head regrows a body, this is fine from a memory stand point, but then where does the base mateiral and organs to convert and use that material come from?

I think Highlander did it best, the only way to kill an immortal is to remove the head, any other damage won't kill and can be healed/regrown, chop off the head and the "immortal" dies and his power is given to the executioner.


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