Jokaero
The Jokaero are an ape-like race created by the Old Ones a long time ago. It is questionable if they are a truly intelligent race despite being technologically advanced, because they don't possess a language, culture or any greater motivation than bare survival.
It is speculated their understanding about technology is coded into their genes, much like Ork Oddboyz (Mekboyz, Painboyz etc.). Although, they differ from their greenskinned breatheren because their technology isn't from a pile of crap. These space monkeys are somehow potentially more advanced than the entire Imperium, almost all of the Mechanicus, and (in different feilds of technology) most Eldar craftsmen.
They are capable of interstellar travel, and migrate as a pack in large, perfectly geometric spaceships which make use of invisible currents of energy, inherent to the fabric of the universe. While it is rare if they choose to do this, a large percentage of Jokaero live upon these spacecraft. Why they are never engaged in space combat is a mystery.
They create digital weapons (all digital weapons, in fact) which some factions, mainly high-up Imperials and influential Techpriests, make use of. Mainly, rich Imperial snobs will use Jokaero as a Protectorate, a euphemism for forced labor.
Despite this, GW lore says Jokaero are extremely rare, and impossibly illusive to boot. They are fairly analogous to animals, and so are instinctively distrustful of other beings (almost always rightfully so). If you do manage, by some miracle, to get ahold of one of these chimps, and not get cubstomped by their teeny Multilaser rings and bracelets, you still need to manage to keep them. They have a nasty habit of knowing how everything every race could possibly build works and operates, plus things nobody else in the universe knows. Naturally, this means that any prison they are held in is usually short-lived, despite any measures to prevent it. Logic is not a necessary component of the Warhammer universe. This in mind, it is not impossible to work with a Jokaero (and thus aquire more Digital Weapons). If you can convince them you are friendly, they won't run from you and you can essentially roll with them for a while, hopefully getting some Digital Weapon death-bling into the bargain. If you are the gimdark version of Jane Goodall, you might even manage to aquire one as a pet/coworker, seeing as they are a very rare and valuable resouce. However, this is exceedingly rare, and accounting for the vastness of known space, only the wellest-to-do of Rogue Traders, beastmasters, and super-rich, eccentric Imperial Lords have a Jokaero in their possession.
Barring all this, Jokaero are still stereotypically finicky, making doohickies on a whim: sometimes not at all, sometimes for days straight. There is no guarantee that the gadgets it makes will be Digital Weapons, however anything it does make will assuredly be magnitudes more advanced (and smaller) that any Imperial equivalent (if there is one). As said above, the Jokaero mostly make things out of simple survival need: self defence lasers, multi-dimentional backbacks, infrared goggles and the like.
Jokearo in Warhammer 40K Tabletop
Recently, with the Codex: Grey Knights including Jokaero as a possible bodyguard unit for Inquisitors, /tg/ quickly found a loophole in the rules that allowed them to field an entire army of space-orangutans. The result is that Codex: Grey Knights has been jokingly called Codex: Jokaero.
Gallery
<gallery> Image:Karman.jpg|This is a Karman from AT-43 and not, in fact, a Jokearo, but numerous fa/tg/uys have voiced that they intend to use them as proxies for their all-monkey army. <gallery>