{{Enemy Infobox
| image= FileTentacle.jpg|250px
| name= Tentacle
| affiliation= Xen
| type=
| health=N/A
| weapons=Beak (100 per Strike)
| entity= monster_tentacle
| designer=*Chuck Jones
*Doug Wood (script sequence){{IA|19990220144204/http//www.sierrastudios.com/games/half-life/archives.html|''Half-Life'' News|Sierra Studios' official website}}
{{Quote|Hey! Hey, over here! Eat lead, you outer space octopus!|Black Mesa Security Force|Black Mesa security guard|Half-Life|Filec1a4 ba octo1.ogg}}

The '''Tentacle''', is a large alien creature which responds violently to sound and vibrations. It is first seen in a rocket propulsion test chamber, but is also seen through the Half-Life (series)|series on Xen and in other areas of the Black Mesa Research Facility.

FileTentacle pit.jpg|The three Tentacles in the chapter ''Blast Pit''.|thumb|200px|left

A large, green, segmented stalk supports a "head", which ends in a sharply pointed, blade-like appendage and features what looks like an eye and also two small gray tentacles near the sharp blade to grab prey. This "eye" appears to be a sensory organ, although the creature only reacts to sound and surface vibrations. Tentacles usually emanate from pits, into which they can retract when injured or in danger. 

Typically several Tentacles use the same pit, suggesting that they may be appendages of a larger organism. Indeed in ''Half-Life'', after the first Tentacle encounter, the player travels through the chasm the creature had occupied. The Tentacle's body encountered at the bottom of the chasm is somewhat squid shaped, with three stumps that appear to have been severed. Some concept art of the Tentacle, shows it to be cluster of three Tentacles attached to a bulbous base, which matches that encountered in the game. Although Tentacles usually come in groups or clusters of three, single Tentacles are also encountered, and the number of Tentacles present may reflect the size or stage of development of the base, or else a more spread-out being, with Tentacles in various locales. Reasons that could support this assumption are how the Scientist pulled from the control room, when first encountered in the silo, is pulled down into the pit and possibly eaten by the base. Another characteristic could be how it relies on hearing, as the base could be too large to fit through, and relies on keen hearing to pull prey down.

Throughout the Half-Life and Portal universe|''Half-Life'' series, only ten Tentacles have been encountered, of which eight are found in ''Half-Life'' while the other two are found in the expansion game ''Half-Life Opposing Force|Opposing Force''.

In ''Half-Life'', the first encounter is in the chapter ''Half-Life storyline Pit|Blast Pit'' where the player encounters three tentacles in a Rocket Propulsion Silo of Sector D. These tentacles act as a type of boss. As the player's weapons are useless, the player has to risk himself through the Tentacle-filled Silo and reach other places so that he can provide Oxygen, Fuel and Power to the Rocket Engine. After that, the player again has to risk through the same Silo back to the Control Room and Activate the Rocket Engine. The intense heat of the engine kills the Tentacles and the player progresses further.

The Tentacle is later encountered in the chapter ''Surface Tension''. The tentacle here is surrounded with various items. The player has to distract the Tentacle in order to get the items. Later, a Tentacle is found in the chapter ''Interloper'', after the first teleportation in that chapter. It is found outside the cave where the player teleports in. In the same area, three more Tentacles are present. This is the last encounter with the Tentacles and the player has to distract them in order to progress.

In ''Half-Life Opposing Force'', only two Tentacles are encountered. It is in the chapter ''Half-Life Opposing Force storyline Reality|Vicarious Reality'' where the player finds them in an Unconstructed Observation Area. The player has to distract them to pass through.

==Behavior and skills==
In terms of behavior, Tentacles aggressively target prey in the immediate vicinity of their pits.  While searching for prey, they gently tap the surrounding area, but when even the quietest noise or vibration is detected, the Tentacles will furiously and repeatedly strike at the location where noise or vibration was detected.  When a Tentacle comes in contact with prey, it will attempt to pull it with their small gray tentacles near the blade into the pit, presumably where it is consumed and digested. In the game, this behavior is witnessed firsthand by the player when a scientist is grabbed by his leg and taken, screaming, into the pit at the base of the tentacles.

In the game, Tentacles cannot be destroyed with the player's arsenal, but shooting the stalk a few times will temporarily drive the creature into its burrow. Great care must be taken when moving near them, forcing the player either to silently crouch past the burrow or cause a distraction with explosives (preferably hand grenades, as those don't reveal the player's location with sound), allowing the player to sprint out of range. It is a good idea to use this tactic, as tentacles can kill the player with a single strike.

==Behind the scenes==
Chuck Jones designed the Tentacle and the Silo D scene where the creature grabs the scientist and hauls him screaming from Silo D-01's control room. According to John Guthrie, no one at Valve was prepared for anything like this scene. When they saw the effect it had on gamers in sneak previews, they knew they had made the right decision to put animated sequences directly into the game rather than setting them apart in cut scenes.''Half-Life 2 Raising the Bar''

In Online Gaming Review's early ''Half-Life'' Monster of the Week Feature preview, the Tentacle was given the WikipediaTaxonomy (biology)|taxonomic designation "Hypersuctor sensitiva".{{IA|19990222010052/http//ogr.com/specials/monsters/tentacle.shtml|''Half-Life'' - Monster of the Week feature|Online Gaming Review}}

Originally, the Tentacle was able to attack the player through the doorway on the first floor of the silo. The unused attack animation{{abbr3|i|The filename is TENT2_Level1_Door_Reach1.}} can be found in the SDK for the game.

===''Half-Life'' (pre-release)===

FileTentacle silo concept.jpg|The cabal for the ''Half-Life'' chapter ''Blast Pit''.
FileTentacle concept.jpg|Concept art.
FileTentacle alpha.jpg|Early model from Half-Life Alpha|''Half-Life'' Alpha.
FileTentacle render.jpg|High-res model render.
FileBigtent.jpg|The early Barney in the Tentacle pit.
FileBigtent2.jpg|Ditto, another version.


FileGordon tentacles.jpg|Promotional artwork for ''Half-Life'' Dreamcast.
FileC1a4i attack01.jpg|Tentacle attacking a scientist in Silo D.
FileC1a4i attack02.jpg|Ditto, now grabbing the scientist.
FileBarney Tentacles pwnd.jpg|Security guard about to get killed by the Tentacles in Silo D.
FileC1a4g0001.jpg|The base of Silo D's Tentacle, underwater.
FileC2a5x tent.jpg|In the desert.
FileTentacle Xen1.jpg|The first Tentacle seen on Xen.
FileTentacle Xen2.jpg|Tentacles on Xen.
FileOf4a3 dome.jpg
FileTentacle base model.jpg|Base model.

==List of appearances==
*http//youtube.com/watch?v=s1JupoC4-EI ''Half-Life'' 1997 Teaser {{1st}} {{Nc}}
*''Half-Life Opposing Force''
*''Half-Life 2 Raising the Bar''


==External links==
*{{YouTube|-GeQfqyRT-g|Pre-release Tentacle model}}
*{{YouTube|jr4QpHdn8DE|Pre-release Tentacle animation}}

CategoryXen creatures
CategoryHalf-Life Opposing Force
CategoryChuck Jones designs