Strogg

"The Strogg: soulless fusions of decaying flesh, bones and metal, twisted and ruined by centuries of war. They search the galaxy for the sole item their existence requires, harvesting, consuming and destroying everything in their path. And now, they have arrived… here!"
 * — Intro to Quake Wars

The Strogg are the primary antagonists of Quake 2 and Quake 4. They also appear as one of the playable factions in Enemy Territory: Quake Wars. They are a cybernetic race of unknown origin that reproduces by combining biological components from their foes with advanced technology.

Physical Characteristics
The physical appearance of a Strogg is determined by its role in Strogg society. All Strogg have the same basic appearance, however; bipedal humanoids with a large amount of cybernetic implants. Most weapons used by Strogg soldiers appear to be integrated into their right arms.

The physical appearance of the Strogg before they became cyborgs is unknown.

Homeworld
The Strogg homeworld is named Stroggos. By the time of their appearance in the Quake series, the Strogg had stripped the planet of its resources, and it is now a desert wasteland, lacking much of the original ecosystem. It's capital city is based in Cerberon, which was built in a massive crater called Crater Majoris. Despite losing most of its resources, the planet is still home to a small amount of savage animal life. There are various military and industrial facilities covering its surface.

Human-Strogg War
In the mid-21st century, the Strogg instinct to harvest brought them to planet Earth. The result was a long and bloody conflict that resulted in millions of casualties. The Humans initially believed the Strogg were there to strip the planet of it's natural resources, but after capturing some Strogg ships, learned the true motive for the invasion.

Strogg Invasion of Earth
Despite SETI recently announcing that non-terrestrial radio signals had been detected just outside the Solar System's asteroid belt, the appearance of a Strogg Slipgate in Earth's orbit, which then poured forth hundreds of Strogg ships, took the whole world by surprise.

Initially, the Strogg had a distinct advantage over the Humans; the element of surprise was firmly on their side, their technology was much more advanced, and they had an entire fleet in orbit around the Earth. However, the Humans were resilient and resourceful, and managed to prolong the war, buying themselves time whenever and wherever the could.

Over time, the Global Defense Force managed to begin gaining some significant victories over the Strogg. They managed to shut down several planetside stroggification facilities and stroyent production plants. They also began capturing several advanced Strogg technologies, including but not limited to: weaponry, armor, spaceships, and Slipgates. Human scientists then used their skills to learn more about the Strogg, including the location of it's homeworld.

The war on Earth left the planet burnt and forever scarred. Almost every great city was destroyed. The Humans were terrified of a second, more powerful invasion, which would surely be the end of Mankind. However, the Humans were also determined to get revenge on the Strogg, to avenge their dead brothers and sisters, and to deliver payback for what the Strogg did to Earth. The war had become personal for every Human being.

First Human Invasion of Stroggos
The Humans conceived an elaborate plan to have two ships appear in orbit around the Strogg homeworld and begin releasing drop pods with soldiers in them. However, the Human commanders didn't give Strogg technology enough credit, and the attack didn't go as planned. When the Strogg used an EMP device to shut down the drop pods, many Human Marines crash landed miles away from the target area. They were subsequently captured or killed by Strogg armies.

One surviving Marine, nicknamed Bitterman, managed to deactivate the weapon that initially shut down the drop pods. He then proceeded to complete the primary objective of killing the Makron.

With their leader dead and their defenses crippled, the Strogg were in disarray. Despite the high number of casualties, the Humans managed to complete their objective. Another surviving Marine, nicknamed Joker, managed to destroy a Strogg counter-fleet that had been based on Stroggos' moon.

Second Human Invasion of Stroggos
The Human's took advantage of their victories in the initial attack, and planned to lauch a much larger attack that would finish the Strogg once and for all. Unfortunately, the Strogg were far more resilient than the Human's had hoped. A new Makron had been appointed and they had developed a much more advanced system of tactical coordination called the Strogg Communications Network.

The Human's managed to reach the Strogg Nexus, but the EMP that they planned to use to deactivae the Tower was destroyed. The Humans's managed to bounce back, however. They killed the Makron and deactivated the Communications Network.

Since Strogg are designed to take orders directly from their leader through the Network, their now independent armies were severally crippled, as no individual Strogg is known for having the same degree of tactical independece and intiative as a Human soldier has.

Aftermath
Because the Strogg are so resilient, the war is still ongoing and is not expected to end soon. The deactivation of the Nexus likely marked the beginning of the end for the Strogg. Though it is likely that the war will not end until every last Strogg is dead and all remaining facilities on Stroggos have been captured, the victory at the Nexus means that the remainder of the war is likely to just be a mop-up operation against unorganized threats.

That said, however, the Strogg have proven Human assumptions wrong before, and they may do so yet again...

Culture
Strogg culture is almost entirely dominated by a fixation on warfare. Most of the buildings on Stroggos are armoured bunkers, weapon facilities, defences and massive fortifications. One exception is the Palace of Cerberon, which is a prestigious example of Strogg architecture.

Due to the presence of nationalistic banners, it's possible that the Strogg once had a national identity or took pride in their culture. It's possible the Strogg still make and display these banners as a holdover from a past age when they were less enslaved by their technology, since otherwise the Strogg would see them as a waste of resources due to their lack of need for morale and military pride.

Social Structure
In Strogg society, the biggest and strongest individuals are automatically considered superior, and have higher authority. The most superior member of the Strogg race takes on the title of Makron, and has absolute authority over the Strogg civilisation. Larger, more powerful Strogg have little to no respect for their weaker brethren, and will kill or trample lesser Strogg footsoldiers if they get in the way.

Stroggification
Stroggification is a process the Strogg use to convert biological components into more Strogg. The Strogg collect corpses of their enemies and use them to create more soldiers. Irretrievable bodies are processed into stroyent. Stroggification is also practiced on live prisoners of war. Natural limbs are removed and replaced with advanced Strogg technology. Microscopic robots called nanites introduce them to the cybernetic augmentation process, and finally a neurocyte is implanted in the brain, it's purpose is to change their thought process from Human to Strogg.

Stroyent
Stroyent are liquified rations that refuel and feed their cybernateic bodies. It is a cannibal food that is made from any dead matter they can get their hands on.

Medical Research
Most humans who are captured alive are sent to stroggification, though there are those who are much more unlucky. Captives who are not stroggified are forced to undergo mortality tests. Because the Strogg want to study the pain of their victims and their bodies response, Strogg scientists begin removing organs without applying any anesthetic. They also want to ascertain how long the body can last without specific organs. The torture is long and horrific and inevitably leads to the captive's death. Strogg medical research lacks a concept of ethics, and as such they will do anything they think will help them advance the stroggification process, advance their own medical capabilities, or enhance their weapons to be better at killing.

Technology
Compared to Humans, Strogg technology is overwhelmingly advanced. The most advanced of their technology are the Slipgates, which allow them to travel great distances using wormholes. A Slipgate was used to bridge their assault on the Earth. They also employ the use of teleporters that are specially made to only transport Strogg, and will kill any unstroggified Human that tries to use them. Whether or not that is a security feature or a part of Strogg physiology is unknown.

Weaponry
The Strogg have developed a variety of advanced weaponry. Ranging from small, energy-based blasters to fully-functional railguns. When compared to Human weapons research, the Strogg appear to be centuries ahead, and would be easily winning the war if it was not for the limited spread of many of their weapons.

Source
Quake Wiki: http://quake.wikia.com/wiki/Strogg