Germany: semipostals (1943-45) (here overprinted with the Soviet hammer & sickle: Rick asks, 'origin?').
Wikepedia says in Germany, "..the state was known as Deutsches Reich (German Reich) until 1943, when its official name became Großdeutsches Reich (Greater German Reich)..."
GROSSDEUTSCHES REICH BOHMEN UND MAHREN
Czechoslovakia- Bohemia & Moravia
GROSSDEUTSCHES REICH GENERAL GOUVERNEMENT
Poland: German occupation semipostals (1943-44)
GROSZY
(surcharge): Poland (revalidating stamps after currency reform) (1950)
GROUCH
(currency): Turkey {Ghurush}
GT. PRE
(overprint on stamps of Haiti): (1902) {Gouvernement Provisiore (Provisional Government)}
GUADALAJARA
Mexico- Guadalajara (1867-68)
GUADELOUPE
(overprint on stamps of French Colonies): Guadeloupe (1889-91)