The final Xen boss in Half-Life. Quotes from Half-Life 2 suggests that the Nihilanth was a Combine product. Judging by its appearance, a cybernetically and genetically enhanced Alien Controller that had been controlling the Vortigaunts for eons, much like Breen controlled the human race before Gordon managed to destroy the citadel of City 17.
- "Thieves... you all are thieves... you all are..."
- "Alone... not you alone... not you alone..."
- "The last... I am the last..."
- "Deceive you... will deceive you..."
- Nihilanth - a comprehensive Wikipedia entry.