The Beta-5 Division is a cell of the Office of Naval Intelligence's Section Three. Like its parent section, the Beta-5 Division is often responsible for the development and application of top-secret, morally questionable projects. The cell is so secretive that few UNSC personnel, including those within ONI, are aware of its existence.
The Beta-5 Division is charged with operating the SPARTAN-III Program, though many, if not all the SPARTAN-IIIs are placed under the operational command of the UNSC Army. The Beta-5 Division also operates the Asymmetrical Action Group, which was created late in the Human-Covenant War in order to disrupt, disarm, and dissolve Covenant operations. Though the group was initially comprised of unconventional warfare veterans, it eventually recruited Spartans into its ranks; the Beta-5 Division contracted Chalybs Defense Solutions to create a specialized MJOLNIR variant for the AAG's Spartan operators.
The helmet used by Beta-5 security forces, which is derived from the standard CH252 helmet, is a shared asset among the branches of the UNSC Defense Force and has also been adopted as a MJOLNIR variant.
The Beta-5 Division possesses extremely sophisticated decryption facilities.
In April 2609, the Beta-5 operative who possessed the journal, as well as several artifacts pertaining to Noble Team, died; one of this operative's subordinates sent these contents in January 2610 to his cousin, a fellow Beta-5 operative. He warned his cousin about the dangers that possessing the artifacts could cause, as some individuals within Beta-5 Division would be willing to kill to keep their existence a secret.
Beta-5 is a reference to the number seven, as beta is the second letter in the Greek alphabet, and 2+5=7.
 List of appearances
- Halo: Reach (Mentioned only)
- Halo: The Fall of Reach (First mentioned)
- Halo: Ghosts of Onyx (First appearance)
- Halo: Evolutions - Essential Tales of the Halo Universe
 Related Links
- ^ Halo: Ghosts of Onyx, page ??
- ^ a b Halo: The Essential Visual Guide, page 133
- ^ Halo: Reach
- ^ Noble Team performance reports
- ^ Halo: The Essential Visual Guide, pages 29, 62, 101, 103-105, 130, 139, 165
- ^ a b Halo: Reach - The Armory
- ^ Halo: The Fall of Reach, page 55
- ^ Halo: Reach Legendary Edition - journal classification seal
- ^ Halo: Reach Legendary Edition - package contents letter
- ^ Halo: Reach Legendary Edition - journal note