Penal colonies are colonial territories meant exclusively as correctional facilities for convicts. The prisoners are often used for labor in mines or other industrial facilities on the colonies. Vessels are used to transport prisoners, ore and resources between penal colonies are known as prison ships. While none have been explicitly named, the Unified Earth Government is known to have more than one penal colony.
The Covenant has penal colonies of its own. These were used for instance to detain Unmutual Yanme'e, and excavate supplies for the Covenant.  One Covenant penal colony, Weeping Shadows of Sorrow, was used to detain Sangheili.
 List of appearances
- Halo: Evolutions - Essential Tales of the Halo Universe
- The Mona Lisa (First appearance) (Mentioned only)