The term Imperium might refer to:

Original Dune

• the Old Empire
• the Corrino Empire
• the Atreides Empire

Expanded Dune

• the Old Empire/XD
• the Synchonized Empire
• the Corrino Empire/XD

Dune Encyclopedia

• The First Empire
• The Empire of Ten Worlds
• The Empire of a Thousand Worlds
• The Empire of Ten Thousand Worlds
• The Corrino Empire/DE