Halo Alpha
Halo Alpha

“A little slice of Armageddon.”
Will-043, describing FENRIS nuclear warheads

The FENRIS Nuclear Warhead is a type of UNSC nuclear weapon.


FENRIS warheads had super hardened cases to contain the detonation longer and boost the thermonuclear yield.[2] The hardened cases also made them resilient to small arms and explosions, so resilient in fact that they were regarded as useless without the detonation codes. FENRIS warheads are considered low-yield devices.[3]

They may be detonated manually[4] or remotely.[3]


In 2531, the United Rebel Front possessed three FENRIS warheads at Camp New Hope on Victoria. The weapons were recovered during the Raid on Camp New Hope by SPARTAN-II Blue Team.[2]

By 2552, the FENRIS was slated for decommissioning. However as the Human-Covenant war made a turn for the worse and the UNSC's nuclear stockpile dwindled, they were returned to service.[3]

During the Battle of Earth, SPARTAN-II Blue Team recaptured 12 FENRIS warheads from the Covenant at the Centennial Orbital Elevator. At the top of the elevator, six armed warheads were smuggled aboard a Covenant destroyer while another destroyer, Bloodied Spirit was commandeered by Blue Team. The enemy destroyer was destroyed by a combination of internal nuclear detonations and Plasma Torpedo fire. Blue Team then made the slipspace jump to Onyx.[3]

As the Battle of Onyx drew to a close, Kurt-051 manually detonated 2 FENRIS warheads to deny the Covenant access to the Micro Dyson Sphere.[4]


  • Fenrir is a monstrous wolf in Norse mythology.



  1. Halo: Ghosts of Onyx, chapter 24
  2. 2.0 2.1 Halo: Ghosts of Onyx, chapter 1
  3. 3.0 3.1 3.2 3.3 Halo: Ghosts of Onyx, chapter 23
  4. 4.0 4.1 Halo: Ghosts of Onyx, chapter 39