This Unidentified Sentinel variant was an extremely large Sentinel-like machine used by the Forerunners during the Forerunner-Flood war. It is the largest Sentinel variant observed to date, dwarfing the Retriever in comparison. Its armament includes an extremely powerful energy weapon, capable of firing a lightning-fast energy beam at long range and producing an explosion powerful enough to level an entire city.
- The machine is only seen in the Halo Legends episode Origins.
- It seems to be akin to the Enforcer Sentinel (in the sense that it is a large construct with arms), although this unidentified one is much larger and has no visible shielding.
- This Sentinel variant may be an adaptation of the previously unseen Forerunner Tank cut from Halo 2.