The Imperial Infantryman's Uplifting Primer has also been published.
Citadelnote the company that makes all of Games Workshop's gaming products, paints, and hobby tools has several paints named after 40K characters or races, such as Necron Compound (a silvery drybrushing paint) and a red paint called Mephiston Red, after the Blood Angels character.
The Emperor is often called "Emps", "The Big E", or "The Emprah", as a reference to some characters' pronunciation in Dawn of War.
A popular nickname for the blue-armoured Ultramarines is "Smurfs", which logically leads to their Chapter Master being known as "Papa Smurf". By obvious extension the Ultramarine's Chief Librarian Varro Tigurius is "Brainy Smurf" and the Tyranid character "The Swarm Lord" is sometimes called "Gargamel". Roboute Guilliman is everyone's "Spiritual Liege", including yours. Also often referred to as Rowboat/Rawbutt Girlyman by people who are either annoyed with his frequent in-canon praisedespite being dead, confused about how to pronounce his namenote For those of you wondering, it's pronounced along the lines of "Rob-oot Gulley-man". The Gathering Storm video on Guilliman has it instead as "Rob-oot-ey Gill-ee-man", or both.
Thanks to Dawn of War: Soulstorm, "METAL BOXES"note METAL BAWKESES? is now a common catch-all term for tanks. 'Spess Mehreens' and 'Emprah' are often spelt and spoken in line with their famously odd pronunciation in the same game.
Sisters of Battle are 'Bolter Bitches' or 'Nuns with Guns'.
Due to their crescent shape, the Necron flyers are often referred to as "Cronssants". Another reason is that during their debut they were rather overpowered, and one of the terms to describe something overpowered in the game is "cheese". One fan even went as far as to mount actual croissants on flying bases to count as Necron flyers.
Failbaddon the Despoiler: Thirteen campaigns in the vicinity of the Eye of Terror, due to poor writing and invoking the number 13, has been interpreted by Fanon as thirteen failed attempts to escape the eye and outright destroy the Imperium. Despite being billed as the worst of their foes, Abaddon's every major campaign has ended in failure.note While this might be a deliberately ungenerous interpretation, little information has been given on Abaddon's Black Crusades until recent editions added information for us to know that those campaigns were part of the Long Game to undermine the area around the Eye of Terror and gather superweapons. Once Abaddon got what was needed, he allowed his forces to fracture off to pursue their own goals or fight one another, as Chaos is wont to fo. Sometimes known as Failbaddon the Armless, after his tabletop model's reputation for having its arms break off all the time, or "the incompetent fuckwit," for his incompetent fuckwittery.
Shooting phase for the Guard is unofficially called "the laser light show." Similarly, lasguns are called flashlights or laser sights, while flak armour is either cardboard or T-shirts. note A common joke amongst the fans: What do you call a lasgun with a laser-sight? Twin-linked!
On the flip side, they also have the "Eleven Barrels of Hell" Baneblade (which does indeed have eleven gun barrels).
Ork terminology is also popular, given their rather laconic approach to vocabulary: a melee-oriented army is choppy, a ranged army is shooty (or has lotsa dakka), enemies referred to as spikeyboyz, panzees, 'umiez, greyskins, etc.
Several lists have these kinds of names too. Like the Flying Circus (any army with a disproportionate amount of flying monstrous creatures) or Screamerstar (a Tzeentchian army based around a lot of Screamers and Heralds of Tzeentch that is basically a flying deathstar unit that no one can put down).
"Croissant" is another name for the Necron's crescent shaped air units, named after the French pastry.
"Super Friends" refers to more obscene and blatant abuse of the allies mechanic.
Meme Acknowledgment: In a livestream promoting the Rise of the Primarch book, one of the Warhammer Community members mentions the Smurf meme when introducing Roboute Guilliman.
Old Shame: GW regards the Squats and Zoats as "things better left forgotten." However, hints of them do pop up in new material from time to time...
Promoted Fanboy: Matt Ward is an infamous example. Every codex he's touched has had its fluff tortured, turned into Mary Sues, turned into a tabletop sweeper or any combination of the three. The only codex that he wrote that isn't universally despised was the Necron codex, and that's because two editors kept him from breaking the game and the fluff. Despite that, the Necrons still had their ancient Egyptian influence heavily Flanderized. The Sisters of Battle codex that he wrote had the opposite of the usual problems: the lore was solid, but the rules (written by Robin Cruddace) gave them significant nerfs.
Screwed by the Lawyers: Games Workshop's legal team is notorious for its zealotry. Anyone making anything even vaguely reminiscent of their models, even fan conversions for the game, can expect to get a cease-and-desist letter in the mail. They also attempted to trademark the name "Space Marine" and their failure to do so led them to change the name of the Imperial Guard to the more-easily-trademarkable "Astra Militarum." They continued this with the release of the Gathering Storm supplements and the 8th edition rules by changing the Eldar race to the Aeldari (as the word 'Eldar' was coined by J. R. R. Tolkien to describe the elves), the Craftworld Eldar to the Asuryani or simply Craftworlders, the Dark Eldar to the Drukhari, and the Tau race to the name of their homeworld, T'au. Interestingly, the Space Marines weren't renamed and are still referred to as such despite this faux pas of patent law.
Shrug of God: Games Workshop has deliberately left everything regarding the two "missing" Primarchs open for fan speculation. Other Posthumous Characters, like Commander Puretide or the Silent King, get a similar treatment.
Technology Marches On: While Schizo Tech has a lot to do with it, it's painfully obvious that none of the factions have equivalents to military tech and strategic advances since the 80s when the game was first made, and most the Vietnam War. Even Tau drones are limited to the same kind of ranges as remote-control planes. Artillery especially seems to be at a WW2 level at best.
Urban Legend of Zelda: A common internet theory stated that Games Workshop received/continues to receive royalties from Blizzard Entertainment, as the latter used GW's character designs in WarCraft and StarCraft. A variant claims that StarCraft began life as a Warhammer 40,000 game until Games Workshop pulled the license, leaving Blizzard to turn it into a standalone title. While both parties admit that Warhammer and Warhammer 40,000 did provide artistic inspiration, there was never a formal agreement in place between the two companies. Games Workshop developers were rather pleased that someone had liked their work enough to imitate it, so they opted not to press for royalties (this was back in the days before Games Workshop became known for the aggressiveness of their legal team.)