Berserks

Berserks aren't technically a species. They are a self-replicating Von Neumann machines created by an unknown post-WoF civilization with a sole purpose in mind: extermination of any type of sapient species that could potentially become a threat to their makers. They arrived from nowhere and engaged every sapient species known to Mankind in an all-out war of extermination during the Machine Wars. They almost succeeded.
The result of the war was the berserks splitting into a dozen different factions according to the ethical and philosophical differences, that in case of a purely machine entities resulted in a creation of a dozen different subspecies. One of them - the numerically biggest of them all - decided to keep the name of the original berserks and most of their form, though not their mission.

Basic Information

Anatomy

Berserks lack anatomy and morphology in biological sense of the word. They are machines. Unlike the old berserks, the new ones are humanoid machines. Those living in the territory of the Successor Code are merely 'humanoid', their bodies most obviously robotic. Those inhabiting human space tend to go for a much more human-like form, at least on the outside. They always leave their machine nature painfully obvious (through all sort of minor details).
Their 'minds' normally reside on the internal hard drive located within the 'stomach' area. However, they are on the very basic level not bound to the body in the same way as human minds are. They spend the time they are 'offline' (entire days, if they are not needed) in the Network, an overarching Virtual Reality space. Even when online, they live in a state of perpetually augmented reality.
The rest of their body is typically highly customizable. This includes modifying themselves when needs arise, for example berserk that is 'conscripted' will typically replace most of its body with advanced combat systems.

Genetics and Reproduction

Berserk code works vastly different than the ones created by human programmers (and the transcendent codes of the fully sapient AIs). In fact, even the berserk themselves fail to understand it. Because of that, ever since the central berserk forges were all destroyed or lost during the brief civil war at the end of the Machine Wars, berserks are forced to use certain 'emergency' measures to reproduce.
Berserks were capable of creating a limited copy of themselves. That was typically used in case of a group of berserks stranded off in the middle of nowhere, lacking the numbers to man their own equipment. Now it is used for general reproduction. Creation of a 'children' is a troublesome process that often ends with crippling damage to the original code. Because of that - interestingly enough - it has became an increasingly common practice for two (or more) berserks to use their code to create a new, 'patchwork' berserk, limiting damage to their own code.

Additional Information

Geographic Origin and Distribution

Most of them inhabit the territory of the Successor Codes, however a lot of them also decided to throw their lot with the Mankind, inhabiting various more alien-friendly countries throughout the Confederation of Mankind.

Perception and Sensory Capabilities

Berserk's perception is a complicated issue. Berserks living in Human Space tend to go for a relatively simple mix of eyesight, smell, touch, hearing and taste, just like the rest of the Mankind, though typically their senses are superior to those of baseline homo sapiens. However the more military-oriented berserks (and those living in the Successor Code space) typically go beyond that. Massive computer enhancements of the five basic senses, echolocation, minuscule radars, even psychic detection. Everything goes. This mades the berserk infantry very, very hard to sneak upon.

Civilization and Culture

Naming Traditions

Most of the berserks living in the Human Space pick short names, typically one-word long. They are typically 'descriptive' ones to make themselves stand out a bit. An example might be the Innocent or Crystal.

Average Technological Level

Berserks are relatively advanced in terms of technology. However, their problem is that they lost their understatement of their own technology (or at least most of it) in the aftermath of their post-Machine War schism. They possess a large number of autonomous fabricators that can produce a lot of things that verge on archeotechs. But they no longer understand how they work. They are making attempts to reclaim that knowledge, however.

History

Nobody knows who made the berserks. Their semi-divine overlord known as the Prime Code spent an unknown amount of time in the Hyperspace after someone deactivated it and thrown into that dimension as a way of disposing of it. None but Prime Code knew the creators of the berserks. And Prime Code wasn't a talkative god-machine. What's more, it is now dead and buried.
What is known about the mysterious creators is that they weren't a particularly nice group of aliens. They created a self-replicating Von Neumann machines dedicated to extermination of all life (berserk probes, as such concept was called by human science for centuries before). The only issue is that it is not known if that weapon was ever unleashed upon the Galaxy. All that is known is that the Prime Code was at some point rendered inactive and thrown into the Hyperspace.
Eventually it was awakened by something and began furiously replicating itself while also gathering information about the current powers of the Galaxy. Prime Code decided that it was ready in early 2510, unleashing the Machine Wars upon the unsuspecting Galaxy. The war lasted for 21 years. Lamenters and Shades were almost exterminated. Insectoids and Dragons suffered almost crippling losses. Greys were so close to the edge that they were pretty much traumatized. Humanity suffered giant losses but managed to hold the ground.
It is believed that the mysterious creators of the Prime Code left a kill-switch within it. When a set amount of time passed with no contact with the makers, the Prime Code was terminated. It also spread a number of viruses throughout the berserk systems, causing the devastating damage to most berserks. Many of them changed mentally, forcing the unaflicted programs to attempt to purge those faulty ones. Sometimes the 'loyal' programs won. Sometimes the altered ones won.
This split the berserks into a dozen 'schismatic' groups, vastly varied in believes, forms and goals. Some, like Synths, do not consider themselves to be berserks anymore. Others, like the Legion or Techeaters are at this point pretty much one more type of hyperspace threats, little more than different brand of pirates. But the mainline berserks survived, though they were greatly reduced in numbers and territory. Less than 1% of the programs survived. They also lost the ability to reproduce en masse in the 'typical' way.
Most of them banded alongside a number of surviving Successor Codes, taking over former territory of Shades and Lamenters. Some of them later on emigrated, moving to the Human Space.