Skrulls are a shapeshifting race in the Marvel Universe. Now, I know that it's a fantastical world where trees talk and gods of Norse mythology are real, but do the Skrulls follow the law of conservation of matter? Do they encounter issues when shapeshifting into a being significantly larger or smaller than them? Where does their matter go? I realistically don't expect there to be a comic-based answer for this, but has any writer made an attempt to create a scientific, physiological explanation for the Skrulls' shapeshifting abilities?

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    Probably the same place that Hulk's matter goes to - "A pocket dimension"
    – Valorum
    Dec 2, 2021 at 9:57
  • I always thought that the Skrulls only change their appearance, their internal physiology remains all but the same.
    – Shreedhar
    Dec 2, 2021 at 9:57
  • There are probably some internal changes. One group of Skrulls was changed into cows, and the disguise was so good they even produced milk. Dec 2, 2021 at 10:21
  • I suppose it works nearly the same way as any shapeshifter (e.g. Mystique from the X-Men). In the "Avengers: Earth's Mightiest Heroes", not only did they copy the appearance and the memory, they also copied any abilities that person had.
    – Clockwork
    Dec 2, 2021 at 11:14
  • 2
    We work great, thank y— I mean they work great, fellow human, ha ha ha, how about them insert local sports team name huh? Dec 3, 2021 at 12:12

2 Answers 2


This is directly addressed in the Official Handbook of the Marvel Universe (Vol.2 #12).

In short, a Skrull's body is largely comprised of 'unstable molecules' that can be expanded or contracted at will, in order to give the appearance (and rough composition) of a different person or an object, but they aren't actually becoming that thing, rather just a representation of it.

All “true" Skrulls possessed the Deviant gene series which endows them with the ability to alter their size, shape, and color through mental concentration … A Skrull could mentally cause the unstable molecules that comprise his or her body to become pliant, enabling him or her to assume other forms through muscular expansion and contraction. Once a new shape had been assumed, it took a conscious act of will for a Skrull to assume another form or to revert to his or her natural form. Hence, Skrulls did not lose their assumed forms spontaneously when asleep or unconscious. Skrulls only took on the appearance of an object or person and did not take on any of that objects or persons characteristics apart from that. For example, if a Skrull had imitated a metal box. he or she would not actually have become metal or have metal's characteristic hardness. Similarly, if a Skrull had imitated the form of an exceptionally brilliant or strong person, the Skrull would not have acquired that person's strength or intellectual ability.

There was a limit to the size of the object or person a Skrull could imitate. The average Skrull could not distend his or her mass any more than 1.5 times as large a volume as his or her original volume, nor could he or she contract his or her mass any more than 75% volume as his or her original.

You may wish to note that in recent years this info has been largely ignored by comic writers who've made various Skrulls enormous, tiny and all points in between.


From TSR’s Marvel Superheroes Ultimate Powers Book (officially licensed RPG supplement), the “Shapeshifting” power is classified within the general category of “Self-Alteration.”

This is only noted to contrast where it was not included for example within “Energy Control,” Illusory Power,” “Lifeform Control,” “Matter Control,” “Matter Conversion,” or “Matter Creation.” This might suggest that “conservation of energy and mass” plays no role (either in support of or opposing) in the Skrulls’ shapeshifting power. Additionally, shapeshifting doesn’t generally have any relationship to the control, conversion, or creation of matter, either. Likewise, shapeshifting is also no mere trick of light or the mind (which we hope should already be understood). So those are some things, which it is not.

Ultimate Powers describes the shapeshifting power as:

The hero can drastically alter all of his physical parameters (dimensions, appearance, physiology) to achieve any desired shape. Despite appearances, the hero retains his basic chemical composition unless other Powers are used simultaneously, such as S8/Body Transmutation-Self. Example: Hobgoblin of the Shi’ar Imperial Guard transforms himself into a stone wall. Despite its granite-like facade, it’s composed of flesh; instead of chips flying when the wall is attacked, it bleeds. The hero can attempt to change into any form; success is determined by a… the Player can raise the Power rank by limiting the variety of possible forms to which the hero can change. some categories include inanimates, machines, specific alien or animal races, super rings only and so on. Normal duration is determined by Power rank. If the hero attempts a shape that exceeds his normal size limits (I.e. not more than 150% nor less than 50% of his original size), this affects duration, dropping it… This way a hero can attempt to impersonate a fly or a dinosaur; he just can’t do it for long.

There are other “shapeshifting-“ like, adjacent, related, or other similar powers that do some of the things people may have in mind, such as the already mentioned “Body Transmutation-Self” power, which do allow mass to change, powers or physiology to change (gaining powers of the transformed shape, etc), or a whole host of powers which can be used in connection with shapechange to achieve some things described.

Also recall from the Thor/Hercules side-series of Secret Invasion, the Skrulls themselves have their own entire pantheon of alien space gods, who have all manner of divine and godlike powers which they can provide their chosen species of believers.

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    This is an interesting find, but I wonder if there's any evidence that comics authors are expected to follow similar guidelines about size limits, or if this is an invention of the RPG creators.
    – IMSoP
    Dec 2, 2021 at 18:07
  • As general trend, it’s usually the RPG creators interpreting the license’s canon to the game. A notable exception was West End Game’s SWRPG which had been confirmed on numerous occasions for example Tim Zahn in writing Heir to the Empire and by EU creators to use as the “Star Wars bible.” I’m not sure how TSR’s RPG was considered by Marvel Comics. Dec 2, 2021 at 18:12
  • Ultimate Powers does include an introduction by TSR’s David Martin, and it generally suggests Martin was after an encyclopedic representation of entirety of Marvel powers for use in the RPG. Dec 2, 2021 at 18:14

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