500 000 000 Mark Deutsche Reichsbahn

The Deutsche Reichsbahn — the German national railway — became an emergency note issuer during the hyperinflationary peak of 1923, when the Reichsbank simply could not supply enough currency to meet payroll and operational demands. Railway workers needed to be paid, trains needed to run, and notgeld filled the gap. The Reichsbahn was among the largest employers in Germany at the time, which made its scrip some of the most widely circulated emergency paper of the period.

Five hundred million marks sounds extreme until you recall that by late 1923, that sum bought roughly a loaf of bread — and was itself obsolete within weeks of printing.