Nihilanth

The Nihilanth is the final boss character and the primary antagonist in the computer game Half-Life.

The Nihilanth is the controlling intelligence behind the invasion of Earth shown in the game. Hovering silently in an enclosed cavern dozens of stories tall, it has been commanding the forces of Xen and holding open a dimensional rift connecting Xen to Earth, enabling its creatures to attack.

Physically, the Nihilanth resembles a gigantic, oddly-proportioned fetus with its head alone outsizing the rest of the body, and its brain cavity forming most of the head's bulk. Its legs, minuscule in relation to its body, appear either to be vestigial, or are the remains of amputation. The creature sits on a large mechanical levitating contraption consisting of a large base with spikes underneath. Like the rest of the intelligent Xen races, the Nihilanth has a third appendage protruding from the middle of its pectoral chest region. Its unusually long arms end in disproportionately huge hands and fingers, and it wears metallic wristbands, which look similar to bands worn by the Vortigaunts; contributing to the evidence that the Nihilanth was once a slave to an obscure higher power (presumably the Combine, as the Nihilanth moved his army to Xen to escape them) just as it is a master to the Xen races (see transcripts of speech below). Its torso has what appear to be surgical scars, a subject of much debate for fans.

The Nihilanth attacks by launching energy balls, which come in two types: a swarm of blue-colored electrical orbs that causes immense damage, and a slow-moving, green-colored orb (similar in appearance to the teleportation portals constructed in the Black Mesa Research Facility) which homes in on and teleports its target to other sections of its lair populated by Xen aliens. It also uses these green orbs to teleport Vortigaunts and other Xen creatures into its main chamber to help defend it against intruders. This may not be intended as the creatures appear only when the green orb flies into a wall or rock and triggers the teleportation. A series of gold-colored "energy spheres" orbit around the Nihilanth's head, rendering it impervious to damage. These are consumed as the Nihilanth attacks or summons assistance, but specialized crystals within the upper portion of its chamber replenish the spheres as they vanish. If some determined invader destroys these crystals and does sufficient damage to its body, the Nihilanth's head opens up like a flower, revealing a shining, vulnerable brain. Sufficiently damaging its brain destroys the Nihilanth.

Gordon Freeman was tasked with killing the Nihilanth because it was the only force holding the dimensional rift open after the satellite delivery rocket was used by the Black Mesa Lambda Labs to reverse the resonance cascade. It is believed that the Nihilanth's death triggered the portal storms, and Marc Laidlaw has said that they continue to the present day.

Transcript of the Nihilanth's speech
There are several cryptic phrases either spoken or telepathically broadcast by the Nihilanth once Gordon Freeman reaches Xen, but are difficult to understand in-game. Below are transcripts of several speech files extracted directly from the HL1 data packs, followed by speculation as to their possible meaning. Note that these transcriptions may not be entirely accurate, as the exact contents of the Nihilanth's speech are fairly difficult to make out due to unclear articulation.
 * "Comes... another...": Said when Gordon enters Xen for the first time, this might mean that Gordon Freeman is another human to enter this world, as evidenced by human corpses found on the way.


 * "You are man...he is not man...for you he waits...for you...": Most interpret this as a reference to the G-Man, who the Nihilanth implies is not human. This seems extremely likely in light of the facts that the G-Man is the only "man" who is portrayed in Half-Life with any significance besides Gordon himself, and that the Nihilanth's saying this predates any plans for either of the game's two expansion packs. Said when Gordon enters the second part of "Interloper" at the alien camp.


 * "The last...I am the last...": Said when Freeman enters the final part of "Interloper" near an altar with a red portal. It is unknown what is meant by himself being "the last." A fan theory states that it may mean he is the last of his species as nothing else like him is seen on Xen. It could simply be a nod to the fact that he is the final foe in Gordon's path. It is interesting to note that at this portal to the game's last battle, the voices of scientists that Gordon has previously encountered throughout the game can be faintly heard, with no proper explanation as to why.


 * "Win... you cannot win...": Said when Gordon enters Gonarch's lair. The most obvious interpretation would be that this is some sort of taunt to discourage Gordon. However, it might not be about Gordon's ability to slay the Nihilanth or Gonarch, but rather about his ability to stop the Combine or something not yet known.


 * "Done...what have you done...": Said when Gordon enters the chapter "Interloper." This refers to the Gonarch and its defeat. As the Gonarch creates headcrabs, Gordon's interference (perhaps the reason for the name "Interloper") has halted the production of the headcrabs. This could have a major effect since Gordon has fought headcrabs throughout the entire game. Also, the first section of this level is the last time headcrabs will appear, and only a few are seen.


 * "Die...you all die...you all die...": Probably spoken out of anger, may be related to above phrase. This could also reference hostility from the Nihilanth towards the Combine. Nihilanth may also be speaking of humanity in general, implying that humanity will cease to be (either because of him or the Combine). Possibly also referring to the other human visitors to Xen, whose corpses lie scattered around the world.


 * "Now die...now die...now...": Said during the battle with the Nihilanth. Probably said just to intimidate Gordon.


 * "Their slaves...we are their slaves...we are...": Probably a reference to the Combine, as they enslaved the Vortigaunt species prior to the first Half Life game.


 * "The truth...you can never know...the truth...": Seems to suggest that the overall plotline will remain filled with unanswered questions.


 * "Thieves...you all are thieves...you all are...": Similarly vague. Possible reference to one of the crystals from the Nihilanth's chamber that was taken back to Earth, along with countless Xen specimens for zoological study.


 * "Deceive you... will deceive you": This is quite possibly a reference to the G-Man and the way he employs (and uses) Freeman.


 * "Alone, not you... alone, not you... alone": Unknown. Possibly related to a statement by the All-Knowing Vortigaunt, breaking the fourth wall with a reference to the player.


 * "FREEEEEMAAAAAANNN!!!!!": The Nihilanth screams out Freeman's name at the very beginning of the game's final battle, indicating that it knows Freeman by name. (Assuming that the messages are delivered via telepathy, this is quite credible; such an assumption would also explain how the messages come to be in English.)