In Wagner's Ring Cycle, this Norse god is known as Donner
Thor: "Son of Odin and Earth (Fjorgyn), and husband of Sif [for 
more ... which "one time...were known generically as elves" but are more 
accurately... [DOC] [TLE] Symbols in Wagner's "Ring" [PAR] Symbols in Richard Wagner's The Ring of the Nibelung ... For this reason, 
Wagner called Fafner's lair the "Cave of Envy.