Recently, a SF&F user asked this question, about Inhumans vs. Mutants in the Marvel Universe. With the arrival of the Inhumans in Marvel’s Agents of S.H.I.E.L.D. (and an upcoming movie), and Scarlet Witch and Quicksilver’s appearance in two separate movie universes, its a topic that has generated a bit of interest.
This post is an expanded, more in-depth version of my answer to that question. There’s a lot more to Marvel’s mutant population than just mutants and Inhumans, and things can get confusing. Unfortunately, as with most things Marvel-related, it not a simple question to answer. What constitutes a mutant? How many kinds are there? What’s the difference between them? Are they different species? Here, I’ll try to answer all of these questions and more.
One note on the cinematic universes: there are a lot of movie universes based on Marvel material, but I’m only going to discuss two of them here: Earth-199999, the Marvel Cinematic Universe, and Earth-10005, the X-Men Cinematic Universe. These are the only two large-scale cinematic universes that are still active; as far as I am aware, none of the other (now-defunct) movie universes included any type of mutated human. This includes the two Spider-Man universes, the two Fantastic Four universes, etc, all of which I’ll be ignoring from here on out.
The biggest source of confusion, when discussion Marvel’s mutant populations, is that the word does not mean the same thing in the Marvel universe as it does in ours. Lets start by getting a quick definition of what mutant means, in real-world biology, and see where that takes us. According to Wikipedia:
Per this definition, any group of beings who’s genome is a mutated version of Homo sapiens sapiens is, strictly speaking, a mutant. For the purposes of this post, I’ll be using this definition of the word “mutant” to mean all such groups, and more specific terms to identify members of any particular mutant human population.
The question of whether Marvel’s various mutated races are their own species or not is a bit of an open question, both in-universe and out-of-universe. Partly, this is because the line between species and subspecies is quite blurry, and is determined by many factors beyond simple genetics (including geography, ecology, behavior, and in some cases even politics). Characters such as Magneto, for example, consider themselves to be a different species from humans because it fits their agenda better. However, it’s not clear that such a designation is warranted — Magneto had human parents and had children by a human mother. In modern Marvel comics, it’s common to see members of the human-derived races classified as subspecies of humans, though it is different for different groups. I’ll go into more detail on this aspect as we talk about each group.
Marvel’s Main Mutants
In the Marvel universes, when you use the word “mutant“, you mean something quite a bit more specific than biologists would like:
an organism (usually otherwise human) who possesses a genetic trait called an X-gene that allows the mutant to naturally develop superhuman powers and abilities.
These are the humanoid mutants that you see in the various X-Men and related titles. Unless you’re specifically talking about genetics, if you say “mutant” to a Marvel fan, they assume you mean this kind of mutant. They are usually identified as a subspecies of humanity called Homo sapiens superiorUncanny X-Men (1963) #1</a”>2, while during the House of M story-line, Mister Sinister identified them as Homo mutatisSecret Avengers (2013) #10</a”>4).
Canonically, the Inhumans are typically given the binomial name Inhomo supremisInfinity story arc, thousands of inactive Inhumans (or human/Inhuman hybrids) were living all over the world, alongside humans for millenia. It doesn’t seem like these Inhumans had any significant problems appearing human — no medical tests uncovered them, they didn’t stand out as unusually healthy or sick, and they seemed more than capable of having children of their own.
The Inhumans have appeared in most Marvel universes, but not in Earth-10005 (the X-Men cinematic universe); they are restricted cinematically to Earth-199999.
Deviants and Eternals
We’ve already seen how the Celestials interference with proto-human genetics lead to both Inhomo supremis and Homo sapiens superior. More directly, however, the Celestials genetic engineering created two additional mutant races: the Eternals and the Deviants.
Unlike the other mutants, Eternals and Deviants are born with their mutations already expressed. Eternals appear superficially human, but have a similar set of mutated abilities: psionic powers, energy manipulation, and near-immortality. The Deviants, on the other hand, were engineered to mutate rapidly, making each Deviant nearly unique. (The rate of mutation is said to be far more random than even X-gene mutants).