* Germany (obviously!)
* Austria
* Switzerland (along with French, Italian, and Romansh)
* Liechtenstein
* Luxembourg (along with French)
It's also worth noting that German is spoken by significant minorities in:
* Belgium
* Italy (especially in the South Tyrol region)
* Denmark (in Southern Jutland)
* Poland (in the Silesian region)
* Czech Republic
* Hungary
While German is not an official language in these countries, it plays a significant role in the local culture and history.