{{Enemy Infobox
| image=FileSynths full.jpg|250px
| name=Synth
| affiliation=Combine
| type=Cyborg (possibly)
| health=
| weapons=Various
| entity=*npc_clawscanner 
*npc_combineguard (cut)
*npc_wscanner (cut)
| designer=
| voice=
| hidei=
| hidep=
| hideg=

'''Synth''' is the term for a class of alien creatures turned into war machines, and one of the several species that make up the Combine organization. They are officially described as "self-replicating robots that evolve", "created or taken over by the Combine and enslaved during their conquests and wars."''Half-Life 2 Raising the Bar'' Most Synths seem to possess both organic and robotic characteristics, suggesting that they may be the cyborg derivatives of alien races that were previously enslaved by the Combine and assimilated into its armed forces.

FileD3 citadel 050339.JPG|200px|left|thumb|Crab Synths and Mortar Synths being transported on a conveyor belt.

Synths always appear as average to large insect-like or arthropod-like creatures, usually with segmented legs or antennae-like sensory structures, recalling locusts, crabs or similar beings.

It is unknown how many of the Synths presented in the series are 'true' to their initial species or forcefully evolved by the Combine, since the Combine modify their appearance by adding mechanical equipment and weaponry. It is also unclear whether they originally were fully organic or were already cyborg creatures when the Combine enslaved them, and if they all come from the same planet (mirroring the Xen creatures that were also brought from other worlds and, for some of them, also enslaved). The Strider however appears to have a brain, as seen in ''Episode Two'' (this is the only known Synth to possess any "organ" at all). It is also suggested that some were created from scratch by the Combine (the City Scanner for instance bears some design similarities with Synths, while being fully mechanical). 

Synths do not necessarily arrive on Earth after having been modified, as the City 17 Citadel features factories where Synths are modified. For instance, Stalkers can be seen working on Gunships in the lower levels. Synths are also never observed to be "self-replicating" in-game, but seem to be raised and/or manufactured by the Combine.

Their carapace-like flesh is largely immune to small arms fire (with the notable exceptions of the Hunter and Shield Scanner) and bullets striking it produce a metallic 'ping' noise. These outer shells can be ripped open with enough force, however, as demonstrated when Dog tears a Strider's head open in ''Episode Two''. The only weapons that are known to be effective against the larger Synths are explosives (such as the Resistance RPG|RPG, the MP7's secondary fire, or the Magnusson Device) and the Combine Energy Ball.

It is likely that Synths were the primary forces used by the Combine during the Seven Hour War as the human-derived Combine units, such as Overwatch Soldiers, Hunter-Choppers and APCs, would have only started appearing after the Combine rule on Earth had been established.

==Known Synths==
FileDog vs Strider Outlands.jpg|250px|right|thumb|Dog attacking a Strider in the Outlands, as seen in the second ''Episode Two'' teaser trailer.

Various types of Synths have been brought over to Earth by the Combine, and more types of Synths probably exist elsewhere. Some, such as the Shield Scanner, are merely used as scouting or transport and have little to no weaponry, while others, such as the Strider, are fierce war machines. The known Synths are

*Advisor Pod
*Combine Dropship
*Combine Gunship
*Crab Synth
*Mortar Synth
*Shield Scanner

==Behind the scenes==

FileD3 citadel 02084.JPG|200px|right|thumb|Combine Gunship factory in the Citadel.

*According to Dhabih Eng, the team tried to incorporate elements that were neither strictly organic nor purely mechanical to suggest their original organic forms. They did not want to have giant alien creatures with armor attached or implants added, but rather show a forceful evolution of the equipment unnaturally imposed on them by the Combine. In the end, the designs intentionally blurred the line between machine and animal, in their appearance and more importantly their motion and how they reacted to the world around them.

===Cut Synths===

Several Synths were cut from the final game

*Combine Guard (part-human, part-Synth)
*Combine Super Soldier
*Combine Synth Elite Soldier (part-human, part-Synth)
*Unidentified cut Synth
*Wasteland Scanner

===Early Synths===
Several pre-release materials gives some insight about the early Synths.

===="Weather Control Vignette"====

''Raising the Bar'' features a story fragment of the Weather Control chapter given to the developers for design inspiration, relating parts of the Weather Control battle, with early names for the Combine units. For example "mech" seems to stand for the predecessors of the Synth, while "mech carrier" likely refers to the Combine Dropship. The text depicts the mech looking like Dog's cousins, but apparently new-minted and flawless, and with a "head" in quotes, suggesting that it is strangely-looking. Also, at some point in the text, its head pulses with a faint glow as if powering up for energy, then fires, which is very similar to the Strider's warp cannon, added to the fact that it is brought by a "carrier", the Strider being brought by Combine Dropships without their containers. Added to the gun located in its head, it also has mounted guns. This "mech" could be an early version of one the Synth predecessors of the Overwatch Elite, the Combine Synth Elite Soldier, which has been through several iterations with strangely-looking heads and a narrow waist like Dog (as in the picture seen here), or the Combine Super Soldier, also with a strangely-looking head.


A folder called "TBot1" can be found in the model textures files from the playable ''Half-Life 2 Beta'' files, in a folder called "obsolete". This is likely the textures for the early "mech" or (ro)bot from the Weather Control story fragment, a very early NPC, since it bears some similarities with Dog in design, mirroring the Weather Control story fragment covered above. Since Dog is said to be one of the few concepts that went from the first sketch straight into the game with relatively few changes to the design, it could be assumed that the Weather Control mechs are two legged and bear similar colors and same body part plates than Dog, since he was made from scraps from different metal sources, such as Combine metal (an FileDogSheet3.png|old texture file for Dog also shows a "15" like logo FileTBot1 Shoulder.png|also found in the TBot textures).

The textures also suggest a slightly battered robot, show round eyes that recall the City Scanner's eye, and therefore Dog's head, and is overall yellow-colored and seems to have paws-like feet and two legs, also like Dog. The model is however missing, and it is next to impossible to guess its shape from its texture files. The "1" in the folder's name also suggests that there was probably other versions, thus other colors or other conditions, for example non-battered textures. Other texture files suggest that it had an antenna and was equipped with a flamethrower and that some of its intern circuits were to be visible and blue, like the early Combine Dropship the scenes|Combine Dropship, the Crab Synth and the Mortar Synth. The files also suggest a "collar" made of green fabric, with the same fabric on one shoulder and the thighs, which seems peculiar, although it is another example of the old concept of the Combine recycling human materials.

This "TBot" ("bot" implying "robot") seems more mechanical than Synth (sporting several cogwheels and pistons on its bodywork), more in the "Combine recycling human materials" mood of the very early ''Half-Life 2'' storyline and very closer to the "mech" from the Weather Control story fragment, therefore its model was likely an ancestor of the two-legged Synths of big size, the Combine Synth Elite Soldier or the Combine Super Soldier, with strangely-looking heads.


FileTBot1 BallEyeRight.jpg|TBot1's right eye texture.
FileTBot1 Head.jpg|TBot1's puzzling head texture.
FileTBot1 Shoulder.png|TBot1's shoulder texture.
FileAThighPad.jpg|One of the TBot1's collar textures.

===="Alyx Vignette"====
A story fragment from ''Raising the Bar'' is set at the start of the Air Exchange chapter and has Gordon involved in a train wreck when arriving there. Alyx encounters him with her pet Skitch and they are attacked by "tripods" (i.e. Striders) and "Combine Elite", tall shapes looking like metal, and with muffled, almost silent movements. That does fit the description of the Combine Super Soldier, named "Combine Elite" in ''Raising the Bar'', while the Combine Synth Elite Soldier could also fit, since it was also to be an elite Combine unit. As also stated in the book, the Elite was turned into the Overwatch Elite|humanoid unit seen in the final version.

FileGunship logo.png|right|thumb|The Gunship back logo.
FileCombine soldier beta back logo.jpg|right|thumb|Beta Overwatch Soldier version.

Most Synths bear at least one Combine imagery. Gunships and Striders bear the same logo on their back and head, respectively. This logo was on the back of the Overwatch Soldier's old texture (in white) and can also be seen on the shoulder of FileCombine Synth Elite Soldier2.jpg|one of the Combine Synth Elite Soldier versions. Its meaning and whether it is a Combine logo or not or if it proves a closer relation between the Gunship and the Strider are unknown. Other Synths such as the Shield Scanner, the Dropship and the Advisor Pod bear the standard "claw" logo (in dark red for the two first ones and white for the latter), while the Shield Scanner also bears a trimmed "CMB" logo (like the City Scanner). The Mortar Synth, Crab Synth and Hunter bear no logo at all.

As for the cut Synths, the Wasteland Scanner bears the standard "claw" logo (in dark red), and other unknown markings, partially seen in the Overwatch Soldier outfit. The Combine Guard has no logo, while its predecessor, the Combine Synth Elite Soldier, has some informal logos in some of its versions, as well as the Gunships / Strider logo, as stated above. The Sacktick has two informal logos, one on its back, one on its right front leg, not seen elsewhere. The Combine Super Soldier has the number "314" in its concept art (also featured in the Beta Overwatch Soldier outfit), and two red triangles in a red-rounded circle, reused for the Overwatch Soldier outfit, although with different colors. It also has red strips in several locations.


*It could be argued whether the Combine transhuman forces on Earth could be considered as Synths, as the treatment made to humans by the Combine is more or less identical as the one made to the Synth (thus altering and modifying bodies), but it seems that the term "Synth" only relates to the non-humanoid units.

*The term "Synth" relates to words such as "synthetic", "synthesis" or "synthetical". A "synthetic" element is "made artificially by chemical synthesis";http// a "synthesis" is "the combining of separate elements or substances to form a coherent whole";http// and a "synthetical" element is the combination of "separate elements to form a coherent whole".http// The term "synth" could therefore be interpreted as a short for "synthetic".


===Retail Synths===

FileAdvisor pod front.jpg|The Advisor Pod.
FileCombine Dropship.jpg|The Combine Dropship.
FileGunship.jpg|The Combine Gunship.
FileCrab Synth1.jpg|The Crab Synth.
FileHunter.jpg|The Hunter.
FileMortar Synth front.jpg|The Mortar Synth.
FileShield scanner open.jpg|The Shield Scanner.
FileStrider crouched.jpg|The Strider.

===Cut Synths===

FileCombine guard.jpg|The Combine Guard.
FileCombine Super Soldier.jpg|The Combine Super Soldier.
FileCombine Synth Elite Soldier4.jpg|The Combine Synth Elite Soldier.
FileSacktick.jpg|The Sacktick.
FileWasteland Scanner.jpg|The Wasteland Scanner.
FileSynth concept 2.jpg|An Unidentified cut Synth|unnamed Synth.

==List of appearances==

*''Half-Life 2'' {{1st}}
*''Half-Life 2 Raising the Bar''
*''Half-Life 2 Episode One''
*''Half-Life 2 Episode Two''

{{Imagecat|Synth images}}