The Tarnhelm is a magic helmet in Richard Wagner's Der Ring des Nibelungen (written 1848–1874; first perf. 1876). It was crafted by Mime at the demand of his brother Alberich. It is used as a cloak of invisibility by Alberich in Das Rheingold. It also allows one to change one's form:

• Alberich changes to a dragon and then a toad in Das Rheingold, Scene 3.
• Fafner changes to a dragon after the end of Das Rheingold and appears thus in Siegfried Act II. (It is never made clear whether Fafner actually used the Tarnhelm to transform, or simply transformed as many giants and gods did in the myths. There is also no Tarnhelm present in the original Andvari myth from Reginsmál in the Poetic Edda from which Wagner drew inspiration for this scene.)
• Siegfried changes to Gunther's form in Götterdämmerung Act I, Scene 3.

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Finally, it allows one to travel long distances instantly, as Siegfried does in Götterdämmerung, Act II.^[1] The stage directions in Das Rheingold and Siegfried describe it as a golden chain-mail helmet which covers the wearer's face.

Nacht und Nebel ("Night and Fog") was a directive of Adolf Hitler on 7 December 1941 that was originally intended to remove all political activists and resistance "helpers"; "anyone endangering German security" throughout Nazi Germany's occupied territories. The name was a direct reference to a magic spell involving the "Tarnhelm" ("stealth helmet") from Wagner's Rheingold.

• In The Lord of the Rings, Éowyn adopts the name "Dernhelm" when she masquerades as a man before slaying the Witch-King of Angmar; "Dernhelm" is the Old English equivalent of "Tarnhelm".^[2]

• Huliðshjálmr (concealing helmet) of Norse dwarves
• Fafnir's helmet Aegis