- "Your father was a filthy colo and your mother was a hole in the wall!"
- — A sexual insult in Sangheili culture
The colo is an animal that is farmed across Sanghelios for its meat. Healthy colo are said to have long, glossy coats.  The Office of Naval Intelligence was able to import some of the animals to ONI Research Facility Trevelyan, to be bred for their meat. The colo grown on Trevelyan were genetically modified by ONI's bioweapons team to make them indigestible to Sangheili, and would have been used to starve Sanghelios' population if ONI's program of internal dissent did not succeed. The meat of these genetically modified colo was given to Jul 'Mdama during his imprisonment at Trevelyan, to test the effects of the now poisonous meat.
List of appearances
- Halo: The Thursday War (First appearance)
- Halo 5: Guardians (Mentioned only)
- Halo: Legacy of Onyx (Mentioned only)
- Halo: Bad Blood (Mentioned only)