The German Class 99.73-76 engines were standard locomotives (Einheitslokomotiven) in service with the Deutsche Reichsbahn for Saxony's narrow gauge railways. Together with their follow-on class, the DR Class 99.77-79, they were the most powerful narrow gauge locomotives in Germany for the 750 mm track gauge.

The Einheitsdampflokomotiven, sometimes shortened to Einheitslokomotiven or Einheitsloks, were the standardized steam locomotives built in Germany after 1925 under the direction of the Deutsche Reichsbahn-Gesellschaft. Their manufacture made extensive use of standard design features and components.