Alberich changes to a giant snake 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 no Tarnhelm present in the original Andvari myth from Reginsmál in the Poetic Edda from which Wagner drew inspiration for this scene.)
The stage directions[citation needed] in Das Rheingold and Siegfried describe the Tarnhelm as a golden chain-mail helmet which covers the wearer's face.
In popular culture
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."