- You may be looking for Planetary empire or Interstellar empire.
A space empire was an empire which spanned through space. In the 26th century, the Daleks recognised Earth and Draconia as two well-matched space empires. The Daleks, with the assistance of the Master, plotted to start a war between the two empires, destroying them and allowing the Daleks to emerge and conquer Mutter's Spiral. However, they were foiled by the Third Doctor. (AUDIO: The Dalek Conquests, TV: Frontier in Space)