From Halopedia, the Halo wiki

343 Guilty Spark.


Caretaking, maintenance, security, combat support


58 centimetres (22.9 in)[1]


51 centimetres (19.9 in)[1]


Pulse weapon; Monitor laser weapon


Extremely strong casing; advanced energy shield capable of repelling all conventional weaponry


"Greetings! I am the monitor of Installation 04. I am 343 Guilty Spark."
343 Guilty Spark introducing himself to John-117[2]

A monitor is a general-purpose Sentinel, containing a high-tier artificial intelligence construct, or ancilla.[3]

The Covenant refer to monitors as Oracles; they revere the "Oracles" for their wisdom and believe that they are key to the fulfillment of the Great Journey.[4]



Image of a group of monitors and Forerunner Lifeworkers.
Several installation monitors among Forerunners.
Illustration of a Monitor, Warfleet pages 6-7.
A cross-sectional diagram of a Monitor.

A monitor's body consists of a roughly spherical shape that is concave on three sides, with an illuminated photoreceptor located on the front of the orb. A monitor's silvery metal covering is reminiscent of other Forerunner constructs, though their spherical shapes stand in contrast to the polygonal, angular shapes commonly seen in other Forerunner creations. Some parts of a monitor are elaborately designed, while other parts are intricately simple.[5] Monitors were generally 58 centimetres (22.9 in) in length and 51 centimetres (19.9 in) in height,[1] however some differed in size; the Warden was smaller than average, for example.[6]

The photoreceptors of a monitor vary in color, including blue,[2] red,[7] orange,[8] yellow,[8] white,[8] green,[6] and purple.[9] However, some, if not all monitors' photoreceptors can change color; for example, the photoreceptors of 343 Guilty Spark and 859 Static Carillon were both generally blue, though they turned red when they were in combative states.[10][11] 2401 Penitent Tangent's[7] and 686 Ebullient Prism's[12] photoreceptors were perpetually red, despite no evidence of combat-related behavior.[13] The Warden's photoreceptor was dull green.[6]

343 Guilty Spark and 2401 Penitent Tangent both possessed high-pitched, tinny voices. 049 Abject Testament's voice also had a tinny quality, but was notably deeper.[8]

The central core of the monitor is known as the encephalon.[14]

Functions and capabilities[edit]

Six of the Halo installation monitors gather. Each monitor is represented by a colored dot in surrounding the Forerunner glyph.

Should a monitor be damaged, it is capable of self-repair.[15] The most significant command monitors were often backed up in multiple duplicates; should one of them be destroyed, its consciousness would continue to exist in another physical shell.[16] While monitors are authorized to use all recovery measures available to them at the facility they are assigned to, the construction of new or replacement monitors must be approved by fleet command.[17] Monitors are given access to their assigned installation's translocation grid, allowing them to quickly move across the span of the installation. For long-distance travel outside their installations, monitors are equipped with impulse drives.[18][19]

Monitors' software intrusion capabilities are significantly beyond those of the defenses of the modern-day UNSC; even in a barely functioning, all but destroyed state, 343 Guilty Spark bypassed the Office of Naval Intelligence's AI-enhanced computer security aboard UNSC Rubicon with startling ease.[20] The UNSC team interrogating Spark was also completely unable to extract data from the Forerunner AI without his own volition, remarking that merely probing through the firewalls' outer fractals would take "a million years" in addition to their computers' total inability to mimic the monitor's central controller.[21] Over the course of these intrusions, Spark was also able to covertly upload his personality construct array into the ship's computers and take control of the ship; this did not become apparent to the ship's AI or the crew until moments before the monitor announced its plan to them.[22] Spark subsequently uploaded himself into a damaged armiger recovered by the Rubicon after the ship crashed on Geranos-a. The armiger became his primary form with Spark displaying the ability to take control of the Ace of Spades even in that body. With the help of the crew, Spark later gained the ability to project a holographic avatar on holotables on the ship as an alternative to using his armiger body to interact similar to how a human-created AI interacted through holographic avatars.[23] Similarly, 686 Ebullient Prism was able to infiltrate the UNSC smart AI Iona's secondary personality interface and overpower her within her own system.[24] Monitors were capable of entering cycles of hibernation.[25]

343 Guilty Spark uses his laser weapon to kill a Kig-Yar attacker.

Monitors have a remarkable resistance to small arms fire, though they will eventually succumb after taking extensive damage. On Installation 08, John-117 was only able to destroy 343 Guilty Spark after multiple discharges from an M6 Spartan Laser—a weapon that can destroy tanks with a single discharge—demonstrating that monitors can sustain damage from high-powered weaponry.[26] However, even Spark's badly damaged shell survived to be recovered by the Rubicon though it eventually shut down and Spark uploaded himself into the ship's systems.[27] During the Battle of Line Installation 1-4, Reff 'Talamee severely damaged 686 Ebullient Prism's photoreceptor and casing with an Aggressor Sentinel's weapon; the monitor was eventually destroyed by its own installation's main weapon.[24] When his data stores were damaged, 000 Tragic Solitude noticeably suffered a severe adverse reaction to it and finally agreed to stop the Invasion of Earth in exchange for an end to an attack on his data stores. The attack caused the monitor to shoot through the air erratically with its light flickering on and off.[28] The monitor was destroyed when Bobby Kodiak leapt onto him and plunged his bladed forearms deep into Solitude's housing. The blades penetrated his entire frame and inner components, causing Solitude to rise high up into the air, screaming at an extremely high pitch and then plunge headlong into the ground at an incredible speed and violently explode.[29]

Though monitors are assisted by other constructs in the event of a Flood outbreak, the monitors also have their own offensive capabilities. Their primary armament is a red-colored directed energy beam that is capable of depleting the energy shield of a Mark VI MJOLNIR armor suit in a single blast, as well as mortally wounding a human with lesser armor.[26] This weapon can also kill a Flood combat form almost instantaneously. Monitors also possess two types of utility beams. One of these beams allows a monitor to manipulate and levitate objects.[10] The second is a blue beam that can unlock doors in Forerunner installations and can repair some technology.[30]

Though monitors typically have full control over their installations, this can be subverted under certain circumstances. During Operation: FAR STORM in 2555, Huragok Drifts Randomly was able to seize control of Installation 00 from its monitor 000 Tragic Solitude by bypassing the monitor's security emplacements and tapping into the Ark's core systems, though it was extremely difficult as Solitude was clever at rerouting functions. However, Solitude had taken direct control of the fleet of Retriever Sentinels he sent to attack Earth, preventing Drifts from stopping them.[31] Solitude was unable to retake control of the Ark on his own and attempted to negotiate having Drifts restore control to him through Olympia Vale without success. In turn, Vale believed that Drifts would, with enough time, be able to expunge Solitude from the Ark's systems, terminate his operability and take control of the Retrievers.[32]

Similar to what happened with Solitude, after Cortana arrived on Genesis, she was able to seize control of the installation from its monitor, 031 Exuberant Witness. Exuberant Witness was able to retain some control of the systems, such as using the teleportation grid to transport an M820 Scorpion tank and controlling doors and activating light bridges.[9] She was later able to help guide Fireteam Osiris in attempting to release the Cryptum holding Blue Team, though the override required a Reclaimer to work. After the attempt failed, Exuberant Witness was able to determine that her master access was being blocked through a nearby communications relay. Cortana was able to seal doors leading to the relay against Exuberant Witness' control, but after Osiris activated two auxiliary consoles, Exuberant Witness eventually managed to override the doors. If the consoles had not been activated in time, Cortana would've been able to lock Exuberant Witness out of the system completely. Once the communications relay was destroyed by Osiris, Exuberant Witness was immediately able to regain control of Genesis' systems.[33]

Behavior and personality[edit]

Ussa 'Xellus: "The Ring installations. Do you know where these Rings are?"
Enduring Bias: "That information was taken from my memory when I was brought here. There were security concerns. I have only a partial knowledge of the Rings now, Much was eliminated. It's very disagreeable, having the gap and one probes and finds nothing where something should be."
Enduring Bias informs Ussa 'Xellus about the knowledge limit placed on monitors[34]
Image of a monitor conversing with a Forerunner Lifeworker.
A monitor facing a Forerunner Lifeworker.

Monitors are extremely intelligent, but are also highly devoted to their original functions and protocols; this results in a zealous attitude toward containment of the Flood and, in the case of Halo installations' monitors, an overeagerness to activate the Halo Array should the need arise. Monitors frequently cite protocols as explanations for their actions, no matter how impractical; this has been known to confuse or annoy individuals who have interacted with them. It is possible that a Halo's monitor sees its protocols as the only options in a situation; during the Battle of Installation 04, 343 Guilty Spark could have taken numerous precautions to prevent the Flood from spreading across the installation, but the only action he ever considered was the activation of the Halo.[Note 1] During the Battle of Line Installation 1-4, 686 Ebullient Prism frequently informed his human and Covenant prisoners that they would be killed and dissected in an effort to find immunity to the Flood, showing no concern for the subjects' well-being.[24] The monitors' adherence to protocol is also shown in their seemingly standardized method of introducing themselves: "Greetings. I am [number] [name]. I am the monitor of [installation name]."[35][36][37]

Guilty Spark aided humanity on several different occasions.

Some monitors were intrigued with other sentient species; Enduring Bias initially wished to study the Sangheili upon first encountering them.[38] 343 Guilty Spark sought to learn about the Covenant, and the history of the Sangheili race.[39] He also wished to interact with and learn about the occupants of a ship that crashed on Installation 04, but did not as protocol forbade it.[40] Some monitors made the conscious effort to respect their allies and adhere to their cultures and customs. Enduring Bias learned the societal traditions of the Sangheili and spoke with a male voice, knowing that it would gain him more respect among the species.[34] 343 Guilty Spark later followed the commands of his UNSC and Sangheili allies, and expressed his condolences to John-117 when his attached AI was in danger.[10] 031 Exuberant Witness expressed alarm at Cortana's plans to use the Guardians to enforce the Mantle and assisted Fireteam Osiris in rescuing Blue Team. She also expressed worry for Blue Team's safety when Cortana teleported Blue Team closer to her position as it would push the Warden Eternal beyond all restraint. Exuberant Witness expressed hope that together the Spartans could stop Cortana from enslaving the races of the galaxy.[9][33]

Monitors, like most forms of AI, are susceptible to rampancy.[41] After his defeat at the hands of a joint UNSC-Swords of Sanghelios force, 000 Tragic Solitude appeared to descend into a state of rampancy where he lost all reason and claimed that he had made the mistake of trusting "your kind" before, that "I am the Ark" and accusing everyone of betrayal.[29]

Similarly to a human "dumb" AI, monitors seem to have nearly limitless information of their own expertise, yet apparently lack information that does not pertain to their defined purpose. This is due to the compartmentalization protocols enacted by the Forerunners,[34] which intentionally limit a monitor's knowledge by design so that as little as possible would be divulged should it be captured by the Flood;[30] this measure became particularly essential after the widespread perpetuation of the parasite's logic plague. This data compartmentalization was most prominently demonstrated with 343 Guilty Spark, large portions of whose memories were erased or suppressed after his assignment to Installation 04.[42]


"I have now endured 60,000 years without word from outside the Array. I have no way to know whether we actually saved the galaxy we destroyed. And because of protocol I sat silently while my first chance to be judged for those acts died. To say that I regret being forced to this outcome is a tremendous understatement. But as I perform my inspection of the quarantine lab today, I am reminded of the gravity of my responsibilities."
— 343 Guilty Spark, referring to his requirement to follow protocol over personal desires[43]
2401 Penitent Tangent.
2401 Penitent Tangent.

Monitors were commonly given administrative roles within the Forerunner ecumene. Most prominently, monitors were tasked with servicing and maintaining the Halo installations and ensuring that the virulent Flood stay imprisoned. Beyond their most well-known function, monitors were assigned to a wide variety of tasks by the different Forerunner rates, ranging from robotic household servants to security,[44] combat support,[6] fleet coordination,[45] and duties involved with the Conservation Measure. Monitors also oversee the maintenance and function of many Forerunner facilities, including the Line installations. Monitors are extremely intelligent, yet are completely devoted to their original function; for example, monitors whose duties involve combating the Flood are zealous about containing the parasite, and have been known to turn violently on their allies if they should attempt to violate their containment protocols.

Each Halo installation has a single custodian monitor assigned to it, which oversees all operations on the ring. Line Installation 1-4 was overseen and maintained by a single monitor,[12] as was the Composer's Forge.[46] Numerous monitors were used to provide security for the Forerunners' Capital Court, though they were not essential to proceedings. Monitors were sometimes used in combat by Warrior-Servants,[6] and hundreds were used aboard Lifeworker ships involved with the Conservation Measure.[47] Monitors also served individual households.[48] The Warden was a monitor that served on the Capital that was used to both detain accused criminals and to defend them in court.[49]

Each Halo's monitor commands the Sentinels and other subsidiary defense and maintenance drones based on the installation they oversee.[50] However, despite their post as caretakers of their given facility, the Halo installation monitors do not have the authority to use all available defenses to engage outside threats.[51]

Known monitors and their assignments[edit]

049 Abject Testament, monitor of Installation 03.

Most known monitors are identified by a series of numbers followed by a name. The monitors of the Halo installations have identification numbers comprised of seven raised to the power of the Halo installation's number minus one (7n-1). The names appear to consist of an adjective describing a negative emotion followed by a technological term.[41] In Forerunner communication logs, Halo monitors are identified by their installation's number, a dash, and their own number; for example, 343 Guilty Spark, the monitor of Installation 04, is formally identified on such logs as "04-343."[52]

A list of adjutant submonitors can be found here.



List of appearances[edit]


  1. ^ This behavior may also have been due to 343 Guilty Spark's rampancy. The monitor may have been oblivious to all possible options that did not follow protocol—the Halo's activation may have been the only solution that ever even occurred to him—and he might have been willfully ignoring other solutions.


  1. ^ a b c Halo Waypoint: 343 Guilty Spark
  2. ^ a b Halo: Combat Evolved, campaign level 343 Guilty Spark
  3. ^ Halo: Warfleet – An Illustrated Guide to the Spacecraft of Halo - Glossary, page 90-91
  4. ^ Halo 2, campaign level The Oracle
  5. ^ Halo: Broken Circle, page 34 (Google Play edition)
  6. ^ a b c d e Halo: Cryptum, pages 255-256
  7. ^ a b Halo 2, campaign level Gravemind
  8. ^ a b c d e Halo: Combat Evolved Anniversary, Terminal 2
  9. ^ a b c d Halo 5: Guardians, campaign level Genesis
  10. ^ a b c Halo 3, campaign level Floodgate
  11. ^ Halo: Escalation, Issue #10
  12. ^ a b Halo: Blood Line, Issue #2
  13. ^ Halo 2, multiplayer map Backwash
  14. ^ Halo Infinite, campaign mission Reformation: The Command Spire
  15. ^ Halo: The Flood, page 238
  16. ^ Halo: Primordium, page 314
  17. ^ Halo Waypoint: Catalog Interaction - Page 39
  18. ^ Conversations from the Universe, 343 Guilty Spark's Log
  19. ^ Halo: Combat Evolved Anniversary, Terminal 4
  20. ^ Halo: Primordium, pages 32-33, 168
  21. ^ Halo: Primordium, page 368
  22. ^ Halo: Primordium, pages 377-378
  23. ^ Halo: Renegades
  24. ^ a b c Halo: Blood Line
  25. ^ Halo: Combat Evolved Anniversary, Terminal 4
  26. ^ a b Halo 3, campaign level Halo
  27. ^ Halo: Primordium
  28. ^ Halo: Hunters in the Dark, page 334
  29. ^ a b Halo: Hunters in the Dark, pages 340-341
  30. ^ a b Halo 3, campaign level The Ark
  31. ^ Halo: Hunters in the Dark, pages 313-316
  32. ^ Halo: Hunters in the Dark, pages 324-325
  33. ^ a b Halo 5: Guardians, campaign level Guardians
  34. ^ a b c Halo: Broken Circle, page 93 (Google Play edition)
  35. ^ Halo: Combat Evolved, campaign level 343 Guilty Spark (343 Guilty Spark:"Greetings. I am the monitor of Installation 04. I am 343 Guilty Spark.")
  36. ^ Halo 2, campaign level Gravemind (2401 Penitent Tangent: "Greetings. I am 2401 Penitent Tangent. I am the monitor of Installation 05.")
  37. ^ Halo: Blood Line, Issue 2 (686 Ebullient Prism: "Greetings. I am the monitor of Line Installation 1-4. I am 686 Ebullient Prism.")
  38. ^ Halo: Broken Circle, pages 28-29 (Google Play edition)
  39. ^ Halo 2: Anniversary, Terminals
  40. ^ Halo: Combat Evolved Anniversary, Terminal 5
  41. ^ a b Halo Encyclopedia (2009 edition), page 267 (2011 edition)
  42. ^ Halo: Silentium, pages 314, 330
  43. ^ Halo: Combat Evolved Anniversary, Terminal 6
  44. ^ Halo: Cryptum, page 291
  45. ^ Halo: Warfleet, page 6
  46. ^ Halo: Escalation, Issue #8
  47. ^ Halo: Silentium, page 27
  48. ^ Halo: Silentium, page 220
  49. ^ Halo: Cryptum, page 297
  50. ^ Halo: Combat Evolved
  51. ^ Halo: The Flood, Adjunct - 343 Guilty Spark's log (2010 edition)
  52. ^ Halo 3, Terminals
  53. ^ Halo: Hunters in the Dark, page 198 (Google Play edition)
  54. ^ Halo Encyclopedia (2022 edition), page 358
  55. ^ Halo 3 Legendary Edition, Essentials, Disc Two - Halo: Combat Evolved Cinematics Commentary
  56. ^ My writeup / tour of Waypoint. (NSF56k)
  57. ^ Halo Waypoint: Comic-Con Preview