|designer=Chuck Joneshttp//chuckejones.com/valve.html Chuck Jones' personal website
'''Alien Controllers''', also known as '''Xen Masters''',''Half-Life Prima Guide'' are alien creatures featured in ''Half-Life'' and Half-Life expansions (disambiguation)|its expansions.
Alien Controllers are floating alien creatures. They oversee Vortigaunts and Alien Grunts, and also act as soldiers as part of the Xen military forces. They share many physical traits with other intelligent Xen life forms, especially the Nihilanth, and are related to the Vortigaunts as indicated by their vestigial chest-arms. Their head is disproportionately large and can peel open like a flower to reveal a seemingly mechanical prong, resembling the one seen in the Nihilanth's head. They appear to have three eyes and a vertical mouth similar to that of Alien Grunts.
According to Marc Laidlaw, Controllers are part of the Nihilanth's support network. Since they are partially controlled by it, they may have simply died out after the Nihilanth was killed.http//valvetime.net/threads/info-received-from-valve-only-no-questions-discussion.1298/page-22 ''Marc Laidlaw Vault'' on the ValveTime.net Forums
==Behavior and skills==
Alien Controllers appear to be floating in a meditation pose. They're highly maneuverable and move around a lot to avoid getting shot at. They have two forms of attack. At long range, they shoot a stream of small fireballs from their hands, similar to the Nihilanth's fireballs but weaker and are not too accurate. At close range, they shoot a single larger and more powerful fireball with homing capabilities from their opened head.
In ''Half-Life'', Controllers are first seen when Gordon Freeman is about to travel to the alien world Xen via a teleporter. Gordon has to protect a Black Mesa Science Team|scientist preparing the teleporter. In Xen, Gordon comes across a number of Vortigaunts working in the Mines which, despite being aware of his presence, are not aggressive towards him unless attacked first or they become startled by nearby gunfire. They do, however, resume their normal hostile behavior while in the presence of Controllers. The Nihilanth can summon Controllers for help in the final battle of the game.
In ''Half-Life Opposing Force|Opposing Force'', Controllers are only seen in the teleporter scene from the original game. In ''Half-Life Blue Shift|Blue Shift'', they appear when Barney Calhoun activates the triangulation device on Xen and try to stop him from returning back to Earth. In ''Half-Life Decay|Decay'', they appear and try to stop the players from resetting the dampening locks.
==Behind the scenes==
Alien Controllers were originally referred to as the Flying Vortigaunts Controllers. Their design appears to be inspired by generic 1950s aliens with large heads. The uncorrected proof of ''Half-Life 2 Raising the Bar'' states that the design of the Controller's head derives from the cut Flocking Floater, but this may be an error. Early screenshots show that its loincloth was intended to be blue in color. The final model contains several unused animations, including "block" and "throw" sequences. Controllers were to have their own unique WikipediaGib (video gaming)|gibs. The textures for these gibs can be found in ''Half-Life Source''.
FileController test map.jpg|In a zoo map.
FileController above.jpg|Controller with its head open.
FileAlien Controllers Xen.jpg|Controllers on Xen in the chapter ''Half-Life_storyline''.
FileAlien Controller Xen2.jpg|Controller seen in Mines|the Mines.
FileAlien Controller Xen.jpg|Ditto.
FileAlien Controllers Xen2.jpg|Ditto, attacking Gordon.
FileAlien Controllers Nihilanth teleport.jpg|Controllers seen in one part of the Nihilanth's lair.
===''Half-Life Opposing Force|Opposing Force''===
FileWe Are Not Alone 3.jpg|Controller attacking Gordon.
FileDy dampen0023.jpg|Controllers attacking the player near the primary dampening lock overlooking a Transit System line.
==List of appearances==
*''Half-Life Opposing Force''
*''Half-Life Blue Shift''
CategoryHalf-LifeCategoryHalf-Life Opposing ForceCategoryHalf-Life Blue ShiftCategoryHalf-Life DecayCategoryHalf-LifeCategoryHalf-Life Opposing ForceCategoryHalf-Life Blue ShiftCategoryHalf-Life DecayCategoryXen creaturesCategoryChuck Jones designsCategoryXen creaturesCategoryCreatures