Queen regnant
There has never been a German queen regnant, as women were prohibited from ruling Germany. However Empress Maria Theresa (1745–1780) is often considered to be a ruler in her own right, as she was Queen regnant of Bohemia and Hungary, and despite her husband being elected as Holy Roman Emperor, it was she who ruled the Empire and continued to do so even after the death of her husband before ruling jointly with her son Emperor Joseph II.