Hiwi is a German word, an abbreviation of Hilfswilliger, or voluntary assistant. While it is of common usage in German language, e.g., it is used for volunteer (non-staff) teaching assistants or for college students working part-time in research assignments, it was entered into several languages during the World War II, when German troops enlisted volunteers from the occupied territories for supplementary service (drivers, cooks, hospital attendants, ammunition carriers, messengers, sappers, etc.).

This term from these WWII times is often associated with collaborationism, and in the case of the occupied Soviet territories — with anti-Bolshevism (and widely presented by Germans as such). Some Soviet hiwis were pressed into combat in the ranks of the Wehrmacht in desperate situations, such as with the German Sixth Army at Stalingrad. In some cases they were trusted by the Germans they worked with for their loyalty, but in many cases (e.g., when enlisted from concentration camps) joining the hiwi forces was the matter of survival.

However, Soviet hiwis were referred to as "former Russians" by their countrymen, regardless of the circumstances of them joining, and their fate at the hands of the NKVD was most likely death or the gulag.