Wolverine (Marvel Comics) has an immune system that enables him to survive what most can't, but only if his Mutant Healing Factor is active.
Like his rival Wolverine, Sabertooth (Marvel Comics) possesses an incredible immune system.
Wade Wilson/Deadpool (Marvel Comics)
A child of Wolverine, Akihiro Daken (Marvel Comics) possesses an incredible immune system...
Emma Frost (Marvel Comics)
Laura Kinney/X-23 (Marvel Comics)
Peter Parker/Spider-Man (Marvel Comics)
Steve Rogers/Captain America (Marvel Comics)
Eli Bradley/Patriot's (Marvel Comics)
Bruce Banner/Hulk (Marvel Comics)
Simon Williams/Wonder Man (Marvel Comics)
Jennifer Walters/She-Hulk (Marvel Comics)
Carol Danvers/Captain Marvel (Marvel Comics)
Thor Odinson (Marvel Comics)
Theodore Altman/Hulkling (Marvel Comics)
As sentry guns, the Turrets (New Blood Interactive's DUSK) are immune to various contaminants.
Poison Ivy (DC Comics) is immune to all toxins, including Joker venom.
The Joker (DC Comics) is immune to his own Joker venom as well as many other poisons.
Harleen Quinzel/Harley Quinn (DC Comics)
Slade Wilson/Deathstroke (DC Comics)
The Fork Maidens (New Blood Interactive's DUSK) are all immune to whatever contaminants that are possibly present in hazardous areas due to being undead, especially when it comes to diseases.
Possessed Scarecrows (New Blood Interactive's DUSK) are immune to all sorts of contaminants due to not being organic in nature.
Because they are simply made of air, the Air Elementals (Serious Sam) are immune to all kinds of contaminants, such as viruses, radiation, and among other hazardous byproducts.
Being constructed out of ice, the Ice Elementals (Serious Sam) are immune to every form of contaminant, such as viruses, poisons, and among other hazardous elements.
Due to being made of minerals, the Stone Elementals (Serious Sam) are invulnerable to every single kind of contamination, such as viruses, radiation, and among other hazardous elements.
Since they are made of water, the Water Elementals (Serious Sam) are invulnerable to every single kind of contamination, such as chemicals, poisons, and among others.
Shadow the Hedgehog (Sonic the Hedgehog)
Jake Muller (Resident Evil 6) is immune to the Progenitor virus and its derivatives, most notably the C-virus.
Jill Valentine (Resident Evil series) developed complete immunity to all T-virus derivatives after being infected with the T-virus and cured by the vaccine in Raccoon City.
A Venom Human, Magellan (One Piece) develop a immunity to all known poisons after eating the Doku Doku no Mi.
After surviving being poisoned by Magellan, Monkey D. Luffy (One Piece) has developed extremely powerful antitoxins in his blood that allow him to shrug off most poisons with ease, not including Armored Stonefish.