簡介
屍腦獸被假定為蟲族形態的最高階狀態。只有當接近“臨界質量”的蟲族融合在一起的時候，這一點與原始屍腦獸很相似，但規模更大，屍腦獸才能形成。它通過一種未知的方式，有可能是心靈感應的方式，對整個蟲族發號施令，並充當中心智庫的角色。正因為如此，屍腦獸有可能保存著所有蟲族的記憶，哪怕是那些包含了謎一般“起源”的獨立的個體。儘管屍腦獸有引導整個蟲族的力量，但似乎卻不具備指揮蟲族對抗小規模戰鬥的能力。原始屍腦獸是蟲族野生階段的最高級形態，也稱智慧形態。作為蟲族中少見的一種類型，原始屍腦獸與其它類型有很大差別，完全沒有移動能力的它們顯得十分被動。原始屍腦獸很像是由三種戰鬥形態融合在一起而構成的龐大的球狀組織，外表還附有紡錘體裝的外生結構與周圍環境相粘附。
屍腦獸是蟲族意識形態的化身，肆無忌憚的搜尋、吞噬著星系中一切不尋常的智慧的生命體：為了蟲族本身的繁衍與擴張野心，操縱其他生命體來乾它們的骯髒勾當。第一隻屍腦獸，大概生存於 10 萬年前，被光環的第一次啟動所消滅。隨後第二隻屍腦獸形成，並躲藏於 Delta 光環中，它似乎非常了解先行者們的科技，甚至捕獲了 2401 引導者懺悔切線，改裝了光環上的心靈運輸系統，並了解了光環的構造。這是一隻不同尋常的屍腦獸。
從外形上來說，屍腦獸更像是捕蠅草：它是一個結實的帶有觸角的巨大實體，肥胖的頸部與模糊的腦袋，但其巨大的嘴卻可以用很低沉的語調說話。它龐大的觸手具有強大的力量，並有足夠能力從光環深處擴展至表層上百公里的地方。
意義
原始屍腦獸的寄主與其它戰鬥形態的寄主不同，它們都有特性使得其寄主在精神上能夠對蟲族的同化有一定的抵禦，從而保有一定的原始意識形態。但是，蟲族能夠對原始寄主的記憶進行高度的詳盡分析，過濾出每一條對蟲族有用的信息，並把這種重要信息傳遞給整個蟲族，而這些信息，被原始屍腦獸進一步整合，以制定它們的策略。當蟲族需要執行高級任務，例如駕駛大型戰艦、操作複雜機器的時候，就要首先建立原始屍腦獸。
出場
原始屍腦獸在 HALO 系列中出現和描述過幾次。第一次出現就是 HALO 1 中被蟲族感染的凱斯艦長一關，由凱斯艦長和幾名被感染的人類和精英戰鬥形態蟲族所組成，蟲族需要駕駛真理與和諧號戰艦逃離光環；它後來被星盟的精英特種部隊消滅（小說內容）。第二次出現是在 HALO 漫畫小說，由工程師、野豬獸、人類戰鬥形態蟲族和維修船上的其他動物所組成，準備駕駛維修船逃離，後來被半嘴精英 Rtas 'Vadumee 消滅。第三次出現是在 HALO 2 博愛之城一關，墜落的鵜鶘運輸機駕駛艙可看到。第四次是在 HALO 3 蟲族大門一關，雖然沒有出現，但是駕駛墜落沃城的大型戰艦隻有原始屍腦獸才能完成。
起源
屍腦獸是洪魔的一種形態，因而洪魔誕生就是屍腦獸誕生。
洪魔誕生也不得不說也是一種巧合，起因：先驅被自己視為淘汰品的先行者奇襲並驅離銀河系後，憤怒之餘，重新開啟一個被擱置很久的計畫，他們憑藉自己強大的科技匯聚了至少12種未知生物（這其中也包括一名先驅），創造出了可怕的蟲族-洪魔(Flood)，決定在銀河系釋放這種生物武器作為制裁手段向先行者復仇，並主導一場重估生命發展方向的試煉以判斷他們認為能繼承他們衣缽的種族——人類是否真的能繼承衣缽。
先驅將這至少12種以未知生物為素體組成的蟲族首領“上古屍腦獸 (Gravemind)” 放置於儲存艙，投放在銀河系邊緣的一顆廢棄行星上。它就是後來的永生者 (the Timeless One)，也叫做原基 (Primordial)，而屍腦獸的意識則來自那名融合為蟲族的先驅個體，先行者稱它為受囚者 (the Captive)。它的目的是要將先驅與先行者戰爭的真相告訴想要了解真相的人：衣缽的意義、蟲族的起源、人類的角色、先行者不是衣缽的繼承者、人類在通過測試之後可以繼承衣缽。
種族歷史
在沒有成為屍腦獸時，蟲族的存在相當穩定，它們不會自動增生，但是會在感知生物體的附近形成，尤其是有自我意識及『內觀能力 [?]』的生物體。
而在『野生』階段時，蟲族只能利用『費洛蒙』通訊來進行本體的協調，研究指出，它們傳遞的信息必定無法太複雜。這些個體能夠取得宿主的能力和記憶，一旦蟲族建立出屍腦獸後，便會進入『互助』階段，也就從這時候開始，蟲族的危險性會暴增。遠距不同形態群組的同步化，以及個體間的職業專門化，將不再藉由費洛蒙通訊來進行。因為群組對形勢變化的反應，就戰略層面而言算是瞬間或近乎瞬間完成的，期間完全不會因為距離而有任何的『時間延遲』。根據推論，蟲族在後野生階段擁有某種『心靈感應 [?]』形態，不過目前尚未獲得證實。
屍腦獸，與其前身原始屍腦獸相似，是蟲族超級細胞 (FSC) 及宿主複雜的神經系統的融合體。屍腦獸對自身所創造的機動體的控制能力，就像是一般個體控制自己的四肢一樣。因此，在野生階段時，屍腦獸的控制還局限於個體層面，不過一旦進入互助階段，便會由中央複合智慧發號施令。
雖然目前並沒有任何嚴謹的試驗資料，不過根據實際情報顯示，如果將機動體從屍腦獸中移除，便會回復到野生階段。至於某個屍腦獸的機動體是否會受其他屍腦獸的影響，目前並沒有充分資料可供推論，不過邏輯上應該有可能。儘管如此，由於屍腦獸所有個體均極為相似，且目標都一致，所以幾乎無法找出它們當中的區別。
光環2關卡
•The 士官長 begins to wake up, and sees a red circle of lights on the ceiling of some underground area. He sees that he's being held aloft by a tentacle, and he is brought towards the head of a massive creature: the 屍腦獸.
•科塔娜: "What...is that?"
•士官長 is held in front of the 屍腦獸's head, a mass of fleshy mandibles. It speaks in a deep, gravelly voice.
•屍腦獸: "I...? I am a monument to all your sins."
•As the 屍腦獸 talks, it breathes out Flood spores. Two tentacles bring forth a struggling 提爾·外達密.
•士官長: "Relax. I'd rather not piss this thing off."
•提爾·外達密：“惡魔！”
•屍腦獸 makes loud huffing sounds, and indicates 士官長
•屍腦獸: "This one is machine and nerve, and has its mind concluded." (a tentacle wraps around 士官長's head, then indicates 'Vadamee) "This one is but flesh and faith, and is the more deluded."(turns 'Vadamee upside down)
•提爾·外達密: "Kill me or release me, parasite. But do not waste my time with talk!"
•屍腦獸: "There is much talk. And I have listened. Through rock, and metal, and time. Now I shall talk, and you shall listen."
•It raises two tentacles, one wrapped around a red Monitor, the other merged with an infected Prophet of Regret
•模板:2401PenitentTangent: "Greetings! I am 模板:2401PenitentTangent. I am the Monitor of Installation 05."
•Regret struggles to speak through his excruciating pain
•Prophet of Regret: "And I am the Prophet of Regret, Councilor most High... Hierarch of the Covenant!"
•模板:2401PenitentTangent sees 士官長.
•模板:2401PenitentTangent: "A Reclaimer? Here? At last! We have much to do. This facility must be activated if we are to control this outbreak!"
•Prophet of Regret: "Stay where you are! Nothing can be done until my sermon is complete!"
•模板:2401PenitentTangent: "Not true. This installation has a successful utilization record of 1.2 trillion simulated and one actual. It is ready to fire on demand."
•Prophet of Regret: (to the Arbiter) "Of all the objects our Lords left behind, there are none so worthless as these Oracles!" (yells) "They know nothing of the Great Journey!"
•模板:2401PenitentTangent: "And you know nothing about containment! You have demonstrated a complete disregard to even the most basic protocols!"
•屍腦獸: "This one's 'containment'..." (gives a disgusted huff) "And this one's 'Great Journey'... are the same."
•It lowers its tentacles, and Regret shrieks in fear.
•屍腦獸: (to 'Vadamee) "Your Prophets have promised you freedom from a doomed existence, but you will find no salvation on this ring. Those who built this place knew what they wrought. Do not mistake their intent, or all will perish as they did before."
•At this moment, 'Vadamee stops struggling against the tentacles. He stares somewhat curiously at the 屍腦獸.
•士官長: "This thing is right. Halo is a weapon. Your Prophets are making a big mistake."
•提爾·外達密: "Your ignorance already destroyed one of the sacred rings, Demon. It shall not harm another."
•屍腦獸: "If you will not hear the truth, then I will show it to you. There is still time to stop the key from turning, but first it must be found." (indicates each in turn) "You will search one likely spot, and you will search another. Fate had us meet as foes, but this ring will make us...brothers."
•士官長 and 'Vadamee disappear in teleportation rings. Fade to black, fade in on High Charity.
•A swarm of Covenant ships attack each other outside of High Charity. Fade in on the walkway outside the Council Chamber, Honor Guard Brutes guard the gates from Grunt and Jackal rioters.
•真相先知: "We are, all of us, gravely concerned."
•Cut to Council Chamber. A line of Honor Guard Brutes stand at attention. A cameraman Grunt focuses a holographic camera on Truth as he delivers his propaganda, while the 憐憫先知 watches from aside.
•真相先知: "The release of the parasite was unexpected, unfortunate. But, there is no need to panic. In truth, this is a time to rejoice. A moment that all the Covenant should savor." (raises the Index) "For the Sacred Icon has been found. With it, our path is clear, our entry into the Divine Beyond guaranteed! The Great Journey is nigh..." (the Grunt notices 士官長 appearing out of thin air behind him) "...and nothing, not even the Flood, can stop it!"
•士官長 looks down at the shocked Grunt.
•士官長: "Boo."
•The Grunt yelps, throws up his Needler, and flees. 士官長 catches the Needler and aims it at Truth. Two Brute Honor Guards shield the Prophets with their pikes.
•真相先知：“殺了這個惡魔！”
•The Prophets and some Brutes escape through a gravity lift, leaving two Brutes behind.
•科塔娜: "Brutes! The faster you can kill these Brutes, the better." (士官長 kills one Brute.) "They don't have shield generators, but take them out before... It's berserking!"
•士官長 kills all Covenant in the room
•塔塔羅斯 (Loudspeaker): "The Demon has infiltrated the Council Chamber?! Protect the Hierarchs! Seal the exits!"
•科塔娜: "Oh, I don't think so."
•Side doors open up, unleashing Brutes and Grunts upon 士官長.
•After 士官長 fends off the attackers
•科塔娜: "Put me down on one of the pedestals near the door."
•If you approach where Truth was sitting before:
•科塔娜: "They've locked it from below. There's a door at the other end of the chamber."
•The Spartan approaches the door, and 科塔娜's hologram appears on one of the two pedestals.
•科塔娜: "That Prophet, Truth. He has the Index! You've got to take it from him. Let me get these doors. (The doors open) Go! It will be easier to track Truth if I stay in the network."
•If the player continues to wait:
•科塔娜: "Don't worry. You can pick me up later."
•士官長 fights his way to the ledge where 提爾·外達密 was tortured.
•科塔娜 (COM): "Watch out for the Captain, it's got a Brute Shot!" (Note that the Brute Captain with the Brute Shot first shows up in the Council Chamber on Legendary.)
•科塔娜: "Truth is moving through the lower levels of the tower. I'll reverse this Grav Lift. Drop down, try to cut him off."
•If the player stalls:
•科塔娜: "It's safe, really. Just step in."
•If 士官長 continues to wait around.
•科塔娜: "After that stunt on the Cairo, I know you're not afraid of heights."
•If 士官長 still stalls:
•科塔娜: "Fine, I won't watch. Meet you at the bottom, okay?"
•士官長 drops down the Gravity Lift, kills a pair of surprised Jackals and Grunts, and enters another hallway. More Covenant troops appear.
•塔塔羅斯 (Loudspeaker): "Reinforce all approaches to the holding pens. Slay the Demon on sight!"
•科塔娜: "They're beefing up their patrols. Stay sharp."
•士官長 enters a cross section, but with both left and right doors locked, he continues ahead.
•科塔娜 (COM): "Wait a minute! I'm reading Marine IFF transponders. The signals are originating somewhere below your position."
•科塔娜: "There's another lift in the next room."
•He exits and finds a two-leveled, large room with a Gravity Lift, guarded by Brutes. 士官長 reaches the lift on the lower floor.
•科塔娜: "Here, Chief. Jump in."
•士官長 takes the Grav Lift down. He passes a level, alerting a Brute and a pair of Grunts, and continues down. Immediately he passes another level, and catches a glimpse of a dead Elite Honor Guard Ultra with an Energy Sword lying beside it. He finally reaches the bottom, guarded by a Brute with its back on the Spartan.
•科塔娜 (COM): "There are two groups of Marines in the detention block. I'll zero in on their locations, you neutralize the guards... quietly."
•士官長 clears the Covenant forces on the top level.
•科塔娜: "Chief, come to the lower level. The Marines are just inside, careful of the guards."
•(Note: Some times, 科塔娜 will have you free the Marines in the middle level first)
•士官長 drops down two levels lower, clears the guards outside the doors and enters the brig. After killing the guards, the brig doors unlatch, and the Marine POWs arm themselves with dropped Covenant weapons.
•科塔娜: "Listen up, Marines! 士官長's hunting a Prophet, and you're gonna help him kill it."
•陸戰隊員: "Affirmative!"
•或
•陸戰隊員: "No sense sticking around here!"
•科塔娜: "One more group of Marines to go, Chief."
•The squad exits the brig and are immediately attacked by the guards on the mid level.
•科塔娜: "Chief, come to the middle level. More guards, get ready."
•The team levitates up to the mid level and frees the second group of Marines, who armed themselves, again, with dropped Covenant weapons.
•科塔娜: "That's all the Marines, Chief. Good work."
•科塔娜 (COM): "We'll get out of here the same way we came in - the central Grav Lift."
•科塔娜 (COM): "Hostile reinforcements coming down the lift!"
•The team returns to the highest floor and kill the reinforcements.
•科塔娜: "The lift is clear. Step on in."
•The Marines, one by one, step into the lift and leaves the area.
•If the player stalls:
•科塔娜: "We've got to get after Truth, Chief. Step into the lift."
•士官長 enters the lift and is sent to a room with Marines waiting. The dead Honor Guard Ultra Elite seen earlier still lies on the ground.
•真相先知 (Loudspeaker): "Fear not, my brothers! The Sacred Icon is secure. It was 塔塔羅斯 and his Brutes who took the Icon from the Flood, and for that they have our thanks."
•科塔娜 (COM): "Excellent! Truth is broadcasting on the move. It'll make him much easier to track."
•Three Elites run out of a nearby door, pursued by a lance of Drones. The team eliminates them and enters through the open door. They continue into a hallway, walk pass another dead Honor Guard Ultra lying on the floor, and encounter a pair of Honor Guard Elites fighting some Brutes and another lance of Drones. After all the Covenant are dead, another swarm of Drones emerge from the door and attack the team. The team eliminates them and continues to the next hallway.
•真相先知 (Loudspeaker): "The Elites have failed to protect the Prophets, and in doing so, have put all our lives at risk. Let no warrior forget his oath, 'Thou, in faith, shall keep us safe, whilst we find the Path.'"
•科塔娜 (COM): "I've got a fix on Truth just outside this tower, Chief. There's an exit nearby - hurry!"
•The team enters another corridor, and sees a pair of Brutes and some Jackals attacking a few Honor Guard Elites. They eliminate them and continues onwards, walking past a dead Hunter as they leave the area. They enter another area, guarded by a pair of Hunters, who are eliminated by the team soon.
•真相先知 (Loudspeaker): "With my blessing, the Brutes now lead our fleets! They ask for your allegiance, and you shall give it."
•科塔娜 (COM): "You wouldn't believe the number of kill-systems the Covenant are throwing down around me. Not to worry, it's pretty sloppy stuff. I guess they never expected a hostile intelligence to penetrate their networks from the inside."
•The door in front of the team opens, revealing a duel between an Energy Sword-wielding Honor Guard Elite and a Brute on a platform on top floor of the first Valley of Tears. Eliminating the two as well as the Jackal Snipers in the distance, the team continues downwards, meeting more Elites fighting a Brute under a Deployable lookout tower. Drones fly down and attack another pair of Hunters on the lower floor, but are soon intercepted by a pair of Elite Rangers. The team hikes up and finds a door, guarded by a single Brute. They eliminate it and exit the Valley. Behind the door reveals a wide and long staircase, splattered with purple blood. They walk down the slope.
•科塔娜 (COM): "The Covenant just destroyed two of their own ships! And I'm hearing reports of small arms fire throughout their fleet."
•真相先知 (Loudspeaker): "Creatures of the Covenant: the path is broad, and we shall walk it side by side!"
•The teams exits and finds a Gravity conveyor. They step into it and begin to convey to the other side. A slipspace rupture opens on their far left, and UNSC In Amber Clad emerges from it.
•科塔娜: "Slipspace rupture... It's In Amber Clad!"
•The In Amber Clad flies by overhead.
•真相先知 (Loudspeaker): "Be glad! A reward for all your toil and all your sacrifices is near at hand."
•The team reaches the other side as the sound of In Amber Clad crashing is heard.
•科塔娜: "Hailing... No response. She crashed into another tower ahead of our position. I'll keep trying to make contact, but I'm not registering any human vital signs."
•A pair of Grunts and a pair of Elites turns by the corner and attacks the team. A Brute appears and fires at the Elites. The team eliminates the Covenant troops and reaches the first Hanging Gardens. Intense fighting between Honor Guard Brutes and Minor Elites rages over it. The team eliminates the troops and a pair of Elite Rangers emerges from the tower. After clearing the area, the team continues and encounters another Gravity conveyor. Elites and Grunts emerge, and begin to fire at the pair of Jackals led by two Brutes on the other side, who moves to the side the Covenant Separatists are on. The team eliminates all the Covenant and enters another door. Drones fly by the narrow corridor, unaware of the Human presence.
•真相先知 (Loudspeaker): "At this moment, the Council is gathered on Halo, to see the Icon secured."
•塔塔羅斯 (Loudspeaker): "Rise, pack brothers! Cast down the Elites!"
•真相先知 (Loudspeaker): "There are those who said this day would never come. What have they to say now?"
•塔塔羅斯 (Loudspeaker): "Once the towers are clear, we'll drive them from the lower district!"
•Continuing down the corridor, the team arrives at a small area with a Gravity Lift in the middle of it and plants on the lower level. Drones and Elite Rangers fly in the narrow space, firing at each other. Elite Honor Guards and Special Operation Elites provide support fire, but are soon intercepted by a pair of Brutes and two Jackals. The team clears the area and advances into another narrow corridor. Walking out the door, reveals another Gravity Conveyor.
•真相先知 (Loudspeaker): "I have listened to the Oracle, and it confirmed our deepest hope. The Great Journey begins with Halo."
•塔塔羅斯 (Loudspeaker): "The Elites are falling back to the Mausoleum. Fools! Their Arbiter can do nothing for them now!"
•真相先知 (Loudspeaker): "Who would doubt the Prophets? What have they foretold that has not come to pass?"
•They move on to the other side, reaching the second Hanging Gardens. Grunts run around it, attacked by a pair of berserk Brutes. The team continues to the next Gravity Conveyor, and enters a door. Now on the bottom of another wide and long staircase, the UNSC forces are attacked by a few Brutes. Moving up as they eliminates the Brute, they reach the door at the top and arrives at the second Valley of Tears. An Elite defends itself from a Brute and a Jackal Sniper, while another Brute attacks a pair of Grunts near the pond below. The opposite door opens, and three Elites, one of them an Honor Guard, along with with a Fuel Rod Gun-wielding Heavy Grunt, who proceeds to fire at the UNSC forces. Scaling the Valley, the team hikes up a slope, meeting two Energy Sword-wielding camouflaged figures, followed by several Special Operations Grunts. After eliminating the troops, the team enters another door and finds an Elite as well as several Grunts patrolling the area.
•They continue into the Mid Tower, meeting more patrolling Elites and Grunts, who are all Special Operation units, if not Ultras. After being spotted, Brutes and Jackals enter the room, joining the firefight; the team eliminates the patrols and opens the next door. They find a long bridge leading to the Mausoleum of the Arbiter. In the middle of it are Elites fighting Brutes, Jackals and Drones for control of the bridge.
•科塔娜 (COM): "If we're going to catch Truth, we'll need to take a shortcut, straight through the Mausoleum. Look on the bright side: for now, they seem much more interested in killing each other."
•The team continues, but are intercepted by more Covenant Separatists, including a pair of Hunters. The surviving forces enter the Mausoleum and come across a very large fight inside.
•科塔娜: "You might consider sitting this one out."
•After the room is cleared:
•科塔娜: "Hang on, I'm picking up two more transponders. It's the Commander and Johnson! They're closing on Truth's position, Chief! They'll need your help!"
•科塔娜's avatar appears on a pedestal next to the exit.
•科塔娜: "This way, Chief."
•The exit opens, with several cloaked Elites and a sword-wielding Honor Guard Councilor running out. 士官長 kills them and continues through the bridge.
•科塔娜 (COM): "...This isn't good. I’m getting confirmed reports of Flood leaving In Amber Clad's wreckage. Let's get the Index and find a way out of here, before things get really ugly!"
•{Cutscene}
•塔塔羅斯和他的鬼面獸帶著凱斯、{Johnson}}和模板:343GuiltySpark toward a platform where the 模板:ProphetsofTruth和憐憫先知 wait for them, with three Phantoms.
•塔塔羅斯: "Split them up. One in each Phantom."
•Three Brutes do so rather brutishly. Keyes notices 琥珀號 in the tower before being pushed into the Phantom. The two Phantoms take off. 塔塔羅斯 kneels before the Prophets.
•真相先知: "The hopes of all the Covenant rest on your shoulders, Chieftain."
•真相先知 hands 塔塔羅斯 the Index.
•塔塔羅斯: "My faith is strong. I will not fail."
•Infection Forms spring up and rush them. The Brutes spot them and they get ready. The Brute Honor Guards throw their pikes aside and stomp on several of them. 塔塔羅斯 flattens one with the Fist of Rukt. The Brutes manage to shoot or crush most of them, but one gets through and lodges itself to Mercy's throat, knocking him off his throne.
•憐憫先知: (screams in agony)
•塔塔羅斯 reaches to remove the Infection Form.
•真相先知: "Let him be."
•塔塔羅斯 turns to Truth in surprise.
•真相先知：（對憐憫先知）“朝聖之旅可不等人，兄弟……即使你也如此。”
•真相先知 boards the Phantom and the Honor Guard Brutes follow immediately, but 塔塔羅斯 hesitates at the dying 憐憫先知. He looks at the Index, makes his decision, and turns away from 憐憫先知.
•關卡結束
