There are many superheroes (and anti-heroes) in the Justice League who are not from planet Earth, but are residing on Earth - Superman, Supergirl (Krypton), Martian Manhunter (Mars), Hawkgirl, Hawkman (Thanagar), etc.

Are there any canon references (in comic books/movies/animated series) that would suggest one or more of them breathe oxygen like humans, and/or require some other gas present in Earth's atmosphere (Nitrogen, for example)?

PS: My question excludes Kryptonians because there has been something similar asked related to them here and here.

  • I feel like this borders as too-broad as written. Maybe look for any DC character that breathes something other than oxygen (which I personally feel is still too broad, but the community is ok with "any" questions).
    – phantom42
    Commented Jan 25, 2018 at 16:14
  • thanks @phantom42. well, here's what I was actually thinking. It is possible but a little far-fetched that the aliens coming to Earth would have had Earth-like environment (take Mars for example). So I thought maybe what that consumed (like air or even food) may be different. But hey, thats just what I thought. And assumed there might some explanation too.
    – Shreedhar
    Commented Jan 25, 2018 at 16:22
  • This is really broad in that the list of characters you are including with "and a lot more" is, by definition, a lot. Please narrow this question down somehow.
    – amflare
    Commented Jan 25, 2018 at 17:09
  • Presumably, Swamp Thing (and possible Floro/the Floronic Man) require carbon dioxide, as their biology is based on Earth plants. However, I believe you're not just asking about characters the need to breathe something other than oxygen, but actual aliens. (And, of course, Alan Moore wrote that sequence where Swamp Thing travelled to other planets - presumably his body needed the same nourishment as the plant-life from which he constructed his body).
    – RDFozz
    Commented Jan 25, 2018 at 21:08

2 Answers 2


Pre-Crisis Ultra-Boy (from the planet Rimbor) required air to breathe. He could only use one power at a time (plus flight, provided by his Legion flight ring), and outside the atmosphere of a planet, he had to use invulnerability to protect himself from the vacuum.

  • Not quite the question - he required an atmosphere, but was his body using the oxygen in the air like ours was, or something else?
    – RDFozz
    Commented Jan 25, 2018 at 21:09
  • I guess Ultra-boy needed oxygen just like humans
    – Shreedhar
    Commented Jan 26, 2018 at 9:01

If an alien is not using some form of respirator or breathing equipment, it may be assumed that they are deriving whatever they need from Earth's atmosphere. It may be oxygen, or carbon dioxide, or some other combination of gases and elements. It's possible that said elements are not available in sufficient amounts to keep the being healthy, and some form of supplement is being used off-camera. Higher concentration of oxygen can have a intoxicating effect on Earthlings - it's possible a similar effect may occur to alien races not used to the combination of gases in Earth air, tho I can't think of any examples at the moment. The Martian atmosphere is thinner then Earth's - it's possible that the richer atmosphere of Earth may contribute to a Martian's enhanced strength.

In the case of Daxamites, the amount of lead in the atmosphere is highly toxic, and builds up in their system quickly.

Tellus, from the Legion of Super Heroes uses breathing equipment, as he breathes methane. Quislet, as another example, is an energy being, and presumably requires no air at all.

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