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 its 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 players.

The Nihilanth attacks by launching energy balls, which come in two types: a swarm of purple-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 or is destroyed by the player 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 suffers damage from the player, 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 so that all the "energy spheres" are consumed, the Nihilanth's head opens up like a flower, revealing a shining, vulnerable brain. Sufficiently damaging its brain destroys the Nihilanth. Additionally, once the Nihilanth uses up all its golden energy orbs, and cannot replenish them, it can only attack with one electrical orb, instead of a swarm of ten, or a teleportation orb.

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. Some of the comments can be interpreted as having various connotations to Half Life 2. However, an important point to remember here is that the possibility of a sequel was far from people's minds during the production, especially such detailed concepts as the Combine.
 * "Comes... another...": Said when Gordon enters Xen for the first time.


 * "You are man...he is not man...for you he waits...for you...": Said when Gordon enters the second part of "Interloper" at the alien camp. Apparently refers to the G-Man


 * "The last...I am the last...": Said when Freeman enters the final part of "Interloper" near an altar with a red portal.


 * "Win... you cannot win...": Said when Gordon enters Gonarch's lair.


 * "Done...what have you done...": Said when Gordon enters the chapter "Interloper." This refers to the Gonarch and its defeat.


 * "Die...you all die...you all die...": Probably spoken out of anger, may be related to above phrase.


 * "Now die...now die...now...": Said during the battle with the Nihilanth.


 * "Their slaves...we are their slaves...we are..." Probably a reference to the Combine.


 * "The truth...you can never know...the truth..." Most likely referring to the G-Man.


 * "Thieves...you all are thieves...you all are..." Referring to the Crystals that were stolen from Xen.


 * "Deceive you... will deceive you" Probably describing the G-Man again.


 * "Alone... not you alone... not you alone" Likely a comment on the unlikeliness of Freeman, with almost no aid, surviving.


 * "Freeman!": The Nihilanth screams out Freeman's name at the very beginning of the game's final battle, indicating that it knows Freeman by name.