Resistium, (the " Hydrogen " of the 'ultra-elements' which had a nucleus of negatrons and had orbital protons) was first featured in ''The Incredible Planet'' by John W. Campbell, Jr.
Durium, an alloy made from resistium and other ultra-elements from ''The Infinite Atom'' by John W. Campbell, Jr. (and was also used by E.E. "Doc" Smith in later works).
Radium X, the extra-terrestrial element which Dr. Janos Rukh ( Boris Karloff ) made a Death Beam device in the film ''The Invisible Ray''.
In '' Marooned '' by John W. Campbell, Jr., the Jovian exploration ship ''Mercury'' was constructed from Parium and '''Synthium,''' elements which had great Tensile Strength .
Unobtanium , the material from which the ship ''Virgil'' was constructed in the film '' The Core ''. the word ''unobtanium'' is also colloquially used by engineers to describe non-existent materials with desirable mechanical properties ("That shaft would have to be made of ''unobtanium'' in order to carry such a high load").
In the Marvel Comics universe, Wolverine's claws and metal skeleton are made of the super alloy Adamantium.
Neutronium (incredibly dense, degenerate ionised matter) is featured in many works of science fiction.
Bendezium of the Metroid Prime series can only be destroyed by the Power bomb weapon.
Mithril is a super metal from J. R. R. Tolkien 's Middle-earth universe. It is precious and silvery, stronger than steel but much lighter in weight. It first appears in ''The Hobbit'', where it is also called " Silver - Steel ". Its properties were developed in '' The Lord Of The Rings ''.
In '' Warhammer 40,000 '', the Necrons utilize a material called Necrodermis (which translates into "Corpse Skin"), a metal that heals itself, for everything, including their own bodies.
The Yautja (the alien hunter race from the '' Predator '' films) use a super-light metal that can be forged to a Monomolecular Edge .
Chogokin Z (also known as '''Super-Alloy Z''') is the metal utilized to construct the eponymous Super Robot of the anime series '' Mazinger Z '', created with the newly-discovered element Japanium . Other variants include Chogokin New-Z, used to construct Great Mazinger , and Chogokin New-Zα, which was the basis material for Mazinkaiser . Series (and robot) sequel '' Grendizer '' also features an unrelated but still highly similar metal called '''Space Alloy Gren'''.
Rearden metal, a green blue metal 3x stronger than steel used to build rails in the book '' Atlas Shrugged ''.