It can be difficult to tell the good guys from the bad in “Der Ring des Nibelungen,” Wagner’s four-opera saga of greed and mistakes.

It’s even more difficult in the Metropolitan Opera’s current revival of the “Ring,” in which the typically villainous Alberich — the dwarfish Nibelung of the title — is portrayed with nobility and nuance by Tomasz Konieczny, in a stunning company debut.

In “Das Rheingold,” the first of the “Ring” operas, Mr. Konieczny stood out among the large cast not only for his unusually rich characterization, but also for his voice: a sonorous bass, filling the Met with ease and delivered with crystalline articulation. His character returns on Saturday in “Siegfried.”

Peter Gelb, the Met’s general manager, said in an interview that he was “bowled over” by Mr. Konieczny’s performance — so much so that Mr. Gelb immediately invited him to star in Wagner’s “Der Fliegende Holländer” when the opera is revived in a future season after a new production has its premiere next March.