{{Youmayd|the creature|the ''Half-Life'' chapter|Half-Life storyline 18 Nihilanth|Nihilanth (chapter)}}
{{Character Infobox
|image=Hl nihilanth.png
|death=During the Black Mesa Incident
|rank=Supreme leader
|weapons=*Electrical orb (30 per orb)
*Teleportation orb (no direct damage)
|era=Black Mesa Incident
|voice=Michael Shapiro
|designer=Ted Backman''Half-Life 2 Raising the Bar''
|voicesample=Filenil thieves.ogg|220px
{{Quote|The truth, you can never know the truth...|The Nihilanth|Half-Life|FileNil thetruth.ogg}}

The '''Nihilanth''' is the leader of the Xen military forces that invade Black Mesa Research Facility|Black Mesa during the Black Mesa Incident. It acts as the primary antagonist and the final boss in ''Half-Life''.

The Nihilanth is a massive, floating being that resembles an abnormally proportioned humanoid fetus, with a large head atop a smaller body. It shares many physical traits with other intelligent Xen life forms, especially with the Alien Controllers, and is related to the Vortigaunts, as indicated by their vestigial chest-arms, which is why it had a particular ability to control them.http// Marc Laidlaw Vault on Steam Users' Forums (November 14, 2009) It also wears shackles similar to those worn by enslaved Vortigaunts. The Nihilanth's body features what appears to be the remains of some sort of surgical procedure, and its minuscule legs appear to be either vestigial or the remains of amputation.

Some of its backstory was revealed in a series of conversations with the developers. According to Doug Lombardi (restating something that was told him by Marc Laidlaw), the Nihilanth's homeworld was invaded by the Combine long before the events of ''Half-Life'', prompting the migration and takeover of Xen by the Nihilanth.''WikipediaPC Zone|PC Zone'' magazine, September 2005 The Nihilanth, the Vortigaunts, and the Alien Grunts were all from the same world. It was also said the Nihilanth was last of its kind, and some of its predecessors might have been captured by the Combine.http// Marc Laidlaw Vault on forums (January 30, 2007)

==Behavior and skills==
The Nihilanth appears to be floating in a meditation pose. It has two attack moves. The first attack is a stream of purple-colored energy projectiles, similar to the Alien Controller's fireballs, but stronger. The second attack is a large green sphere that teleports the player to other areas populated with aliens. These spheres can be destroyed by the player. The Nihilanth can also summon Vortigaunts and Alien Controllers for help in the battle.

A series of orange-colored "energy spheres" orbit around the Nihilanth's head, and provide it with energy. It uses this energy to protect itself from harm and to attack the player. When this energy runs low (after being attacked by the player), the Nihilanth replenishes the spheres by absorbing energy from one of the Crystal (Xen)|crystals in the chamber.

When the crystals are destroyed, the Nihilanth becomes vulnerable, and its head opens up like a flower after some time, revealing a large energy sphere atop a fleshy prong inside his head, which is its only weak spot. Eventually, the Nihilanth floats up with beams and green spheres coming out of its body and dies in a massive green explosion.

FileHl nihilanthcrystal.jpg|right|thumb|200px|The Nihilanth replenishing its energy.
The scientists suspect there is an immense portal at the borderworld, created by the intense concentration of a single powerful being. Gordon Freeman is sent to kill the Nihilanth to stop the invasion, and close the dimensional rift between the worlds. The Nihilanth regularly contacts Gordon telepathically and speaks to him in English in Xen.

===''Half-Life Decay|Decay''===
Dr. Richard Keller thinks that something is interfering from the other side of the rift, when Dr. Gina Cross and Dr. Colette Green attempt to reset the dampening fields to prevent another cascade. Keller says whatever held the rift open did so with intent, and aliens may not all be here by accident. Furthermore, in the bonus chapter ''Xen Attacks'', the Nihilanth sends two Vortigaunts, drone subjects X-8973 and R-4913, to retrieve several stolen Xen crystals.

===''Half-Life 2''===
The Nihilanth is mentioned by Vortigaunts throughout the game in random conversations. It is revealed through these messages that the Vortigaunts see Gordon as a messianic figure after he liberates them by killing the Nihilanth. This is also the only in-game instance in the series where the Nihilanth's name is mentioned by the characters.

==Behind the scenes==
''Half-Life 2 Raising the Bar'' states that the first part of the Nihilanth's name is reference to WikipediaNihilism|nihilism (from the Latin ''nihil'', meaning ''nothing''), while ''-anth'' is a common suffix that is related to flowers and is a reference to how his scalp peels open like a blossom. Michael Shapiro is uncredited to the Nihilanth's voice. However, it can be verified by listening to the Nihilanth's speech sounds and by changing the speed of its grunting sounds.


FileNihilanth concept.jpg|Concept art.
FileC4a3 nihilanth01.jpg|The Nihilanth.
FileHl nihilanthprong.jpg|The revealed energy sphere inside its head.
FileC4a3 nihilanth03.jpg|The Nihilanth is defeated.

==List of appearances==
===Main games===
*''Half-Life'' {{1st}}
*''Half-Life Decay'' {{Mo}} {{Ho}}
*''Half-Life 2'' {{C|Mentioned only}}

*''Half-Life 2 Raising the Bar''


CategoryXen creatures
CategoryCharacters aware of the G-Man
CategoryTed Backman designs