Parasite Units (Metal Gear Solid V: The Phantom Pain)
The Lone Wanderer (Fallout 3); via barkskin perk
Pokémon that can use Harden (Pokémon)
Pokémon that can use Iron Defense (Pokémon)
Pokémon that can use Iron Tail (Pokémon)
Ghirahim (The Legend of Zelda: Skyward Sword)
Ridley clone (Metroid: Other M)
Iron Boar (Spirit Animals)
Annie Leonhart/the Female Titan (Attack on Titan) hardens her skin into crystal to increase the force of a punch.
After ingesting a serum labeled Armor, Eren Yeager (Attack on Titan) gained the ability to harden the skin of his Titan form.
Kevin 11 (Ben 10) possesses Diamondhead's and Four Arms' skin reinforcement.
Gyanza Rujike (Black Cat) using his Muscle to heavily bulk up his body, that bullets bounce off his skin.
Kenpachi Zaraki (Bleach) hardening his skin with his immense spiritual pressure, injuring an attacking Ichigo's hand in backlash.
Masaki Kurosaki (Bleach) hardens her skin via the Blut Vene technique.
Ichigo Kurosaki (Bleach) using Blut Vene to harden his skin.
Cang Du (Bleach) using his The Iron to harden his skin to block Haschwalth's sword.
Gremmy Thoumeaux (Bleach) using The Visionary to imagine his body hardening to stronger-than-steel.
Whenever he transforms, James Ironside's (Blood+) skin hardens to the point where it can easily withstand blades and bullets.
Ryūichi Sendō (Code:Breaker) using his Epithelial Manipulation to harden his skin texture into steel.
Tenshinhan (Dragon Ball series) hardens his body to withstand Yamucha's barraging kicks.
Son Goku's (Dragon Ball series) Super Saiyan form and ki can harden his skin to the point he can shrug off a point blank shot from Frieza's Death Beam...
...and deflect sword attacks from Future Trunks using only a finger...
...Upon perfecting Ultra Instinct Pefected, Goku could harden his body and make it sturdier on command, to the extent Moro broke his own arm against his chest.
Son Gohan (Dragon Ball series) using his ki and Super Saiyan powers to the point where bullets have no effect on him.
After becoming the Legendary Super Saiyan, Broly (Dragon Ball Z: Broly - Second Coming) reinforces his body with tremendous ki to the point he is completely unaffected by Super Saiyan Gohan's punch in the face.
Torafusa (Fairy Tail) can alter the density of his skin that can not only stop Gajeel's magical iron but break it as well.
Greed (Full Metal Alchemist) can harden his skin by rearranging the carbon in his body to make his skin as hard as diamond.
Using Telekinesis, Sylar (Heroes) reinforces his body to lessen the impact of bullets.
In his final form, Ghirahim (The Legend of Zelda: Skyward Sword) hardens his skin to the point where it can withstand blows from even the Master Sword.
The five ring ÄRM on Garon’s (Marchen Awakens Romance) left hand harden his skin.
Senator Steven Armstrong's (Metal Gear Rising: Revengeance) possesses nanomachines in his body, which hardens and darkens his skin in response to physical trauma.
A member of the Parasite Unit (Metal Gear Solid V: The Phantom Pain) hardens his skin into rock-like armor.
Kakuzu (Naruto) hardening his skin with Earth Style/Release: Earth Spear, to the point that nothing can break through, aside electricity.
Hiruko's (Naruto Shippūden the Movie: The Will of Fire) Steel Release/Style: Impervious Armor technique turns his body into black steel that makes him invulnerable to all weapons.
Blueno (One Piece) using Tekkai/Iron Body to harden his body, causing Tilestone's hammer to shatter upon recoil impact.
A Diamond Human, Jozu (One Piece) hardens his skin by transforming it into diamond.
Monkey D. Luffy (One Piece) using Busoshoku/Armament Haki: Koka to darken and harden his rubbery arm.
With his Kaku Mochi, Charlotte Katakuri (One Piece) can harden his arm using Busoshoku Haki in conjunction with his Mochi Mochi no Mi to make it stronger than regular Haki-imbued arms.
Ash's Metapod (Pokémon) using Harden to harden its shell.
Escavalier (Pokémon) using Iron Defense to harden its skin to iron.
Using Iron Tail, Ash's Pikachu (Pokémon) hardens its tail into iron to deal a devastating physical attack.
Ethan James (Power Rangers: Dino Thunder) hardening his skin to block a sword strike.
The Ultimate Predator (The Predator) can freely harden its skin into armor...
...to the extent of being unharmed by another Predator's wrist blades...
...and machine gun fire.
With mastery over his body, Gabimaru the Empty (Hell’s Paradise: Jigokuraku) can harden his skin, protecting himself from bladed attacks.
As a Shinso Vampire, Tsukune Aono (Rosario + Vampire) can use the Creation ability to harden his skin into steel-like armor.
Tetsuhito Kagiroi (Tenjho Tenge) had his skin hardened to iron levels due to his family's women drinking iron sand for centuries.
Yaya (Unbreakable Machine Doll) can harden any aspect of her body, even if they are not attached to her at the time, rendering her invulnerable to physical attacks.
The Ridley clone (Metroid: Other M) transforms into Black Ridley, hardening his skin to the point nothing short of a Super Missile can harm him.
Ultimate Kevin (Ben 10: Ultimate Alien) possesses Humungousar, Ultimate Humungosaur, Four Arms, and Ultimate Aggeregor's skin reinforcement.