Wagner wasn't of course Jewish, but he feared he might be, via his probable actual father, the actor Ludwig Geyer.

Others were also keen to promote this idea, either as a sardonic revenge (e.g. Nietzsche) or to cash in by satirizing the Master's increasing anti-Jewish obsessions.........

and, ironically, Wagner himself displayed very many of the characteristics for which he condemned the Jews.....

see also Wagner's Magic Lamp

and, for something completely different:

The Economic Hemicycles of the Nibelung