You've probably seen the threads. Someone on Reddit or a Discord server starts speculating about a "fifth Chaos God" coming to the grim darkness of the far future. They point to the Skaven—those chattering, backstabbing rat-men—and wonder if 40k the Great Horned Rat is finally about to become a reality. It makes sense on paper, right? The Skaven are arguably the most popular faction in Warhammer: Age of Sigmar. They just got a massive refresh. But here’s the thing: people are often confusing lore from two entirely different universes, and honestly, the truth is way more complicated than just "space rats."
The Great Horned Rat and the 40k Divide
First, let’s clear the air on what the Great Horned Rat actually is. In the fantasy settings (Warhammer Fantasy Battles and Age of Sigmar), he is the deity of the Skaven. He represents decay, ruin, and the inevitable entropy of all things. After the world-that-was ended, he actually ascended to the main pantheon of Chaos, sitting alongside Khorne, Tzeentch, Nurgle, and Slaanesh.
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But 40k the Great Horned Rat doesn't exist. At least, not yet.
In the 40,000 universe, the "Big Four" Chaos Gods are the absolute masters of the Warp. There isn't a rat-shaped hole in the lore currently being filled by a verminous deity. This is where most fans get tripped up. Because Games Workshop (GW) uses similar iconography and themes across their games, it’s easy to assume everything is 1:1. It isn't. The Warp in 40k is a much more crowded, hostile place where the birth of a new god—like Slaanesh during the Fall of the Aeldari—usually involves the psychic extinction of an entire empire.
If the Great Horned Rat were to manifest in 40k, he wouldn't just be "another god." He’d be a fundamental shift in the setting’s power balance.
Why the Skaven Aren't in Space (Yet)
There have been nods. Little Easter eggs.
Veeery subtle.
In some older 40k books, you might find mentions of the "Hrud." Originally, the Hrud were depicted as crouched, rat-like scavengers with long tails. They used "warp-plasma" and lived in the shadows of the galaxy. For years, players assumed these were the 40k version of Skaven. But then GW updated the Hrud lore. Now, they are strange, time-bending creatures covered in rags—not exactly the chattering hordes of the Under-Empire.
Then there are the "Stryxis." They are nomadic, untrustworthy traders found in the Rogue Trader RPG books. They have a vaguely canine or rodent-like appearance and a complete lack of morality. Again, they scratch that itch for a Skaven-lite faction, but they don't serve a Great Horned Rat.
You have to wonder why GW hasn't just pulled the trigger. The Skaven are a goldmine. They sell incredibly well in Age of Sigmar. Bringing 40k the Great Horned Rat into the fold would essentially print money. However, 40k already has a "swarm" faction: the Tyranids. It also already has a "decay and filth" faction: the Death Guard and Nurgle. Adding Skaven risks crowding the tabletop and the lore.
Nurgle vs. The Great Horned Rat: The Conflict of Interest
A major hurdle for the Great Horned Rat entering the 40k mythos is Nurgle. In Age of Sigmar, there’s a lot of tension between the followers of the Rat and the followers of the Plague God. They both love disease. They both love rot. But their "vibes" are totally different.
- Nurgle is about the cycle of life. He loves you. He wants you to rot so new things can grow.
- The Great Horned Rat is about pure, selfish ruin. He doesn't love anyone. He just wants to gnaw on the roots of reality until nothing is left.
In 40k, Nurgle currently owns the "disease" portfolio. If 40k the Great Horned Rat showed up, he’d essentially be a squatter in Nurgle’s garden. This would lead to a Chaos civil war that would dwarf the Horus Heresy. Honestly, that sounds like a great book series, but it’s a massive undertaking for the writing team at Black Library.
The Vashtorr Complication
We also have to talk about Vashtorr the Arkifane. Recently, GW introduced Vashtorr in the Arks of Omen series. He’s a "demigod" of the Warp who represents industry, soul-forges, and dark technology. He is actively trying to become the fifth Chaos God.
Why does this matter? Because Vashtorr occupies the "techno-horror" niche that Skaven (specifically Clan Skryre) usually fill. If GW is building up Vashtorr to be the next big player in the Warp, it leaves very little room for a rat god who likes to build unstable nuclear-magic cannons.
Could the Great Horned Rat Actually Arrive?
It’s not impossible. Games Workshop loves a "Great Shakeup."
We saw it with the introduction of the Leagues of Votann. People said for decades that "Squats" (space dwarves) would never come back. They were a joke. Then, suddenly, they were reimagined as a high-tech clone-culture and became a core part of the game.
If 40k the Great Horned Rat were to appear, it would likely be through a "shatter the status quo" event. Maybe the Great Rift (the Cicatrix Maledictum) allows a new entity to coalesce from the collective greed and desperation of the trillions of humans living in the hive cities. Think about it. Where do rats thrive? In the dark. In the waste. In the forgotten corners of massive cities.
The Hive Worlds of the Imperium are the perfect breeding ground for a deity of vermin.
The "Skaven in 40k" Kitbash Culture
While we wait for official models, the community has already decided that 40k the Great Horned Rat is real. "Cheesestealer Cults" are a massive thing in the hobby. Players take Genestealer Cults rules and kits, then swap the heads and tails for Skaven parts.
It works perfectly.
Subterranean ambushes? Check.
Unstable, jury-rigged weaponry? Check.
A fanatical devotion to a shadowy, multi-limbed or monstrous deity? Check.
This hobby trend is so popular that it’s almost impossible GW hasn't noticed. Often, what the community kitbashes today becomes a legitimate release five years later. Look at the "GSC" (Genestealer Cults) themselves; they were a fringe bit of lore from the late 80s that got brought back because the demand was undeniable.
What Most People Get Wrong About Chaos Pantheons
There’s this idea that there are only four gods in the Warp. That’s a lie—or at least a simplification. The Warp is an ocean of emotion. There are thousands of minor "godlings" and entities.
The Great Horned Rat wouldn't need to defeat Khorne or Nurgle to exist in 40k. He would just need enough psychic "food" to manifest a presence. If the Imperium continues to decay, and if the "lower classes" of the galaxy continue to live like vermin, the Warp will eventually reflect that.
The Great Horned Rat isn't a person; he's a concept. He's the feeling of something scuttling behind the walls of your room. He's the hunger that makes you betray your brother for a scrap of bread. That exists in 40k in spades.
Expert Insights: The GW Strategy
If you look at the 10th Edition and the upcoming 11th Edition rumors, the focus is on "expanding the scope." GW is moving away from just "Space Marines vs. Chaos Marines." They are leaning into Xenos threats and weird, warp-adjacent horrors.
The introduction of the Great Horned Rat would be a "Break Glass in Case of Emergency" move. If sales ever dipped or if the lore felt stagnant, "Skaven in Space" is the ultimate trump card. It's the most requested faction crossover in the history of the hobby.
How to Follow the Lore Without Getting Confused
If you want to stay on top of whether 40k the Great Horned Rat is actually becoming a thing, you need to look at the "Campaign Books." Forget the rulebooks for a second. The narrative progression happens in supplements like Psychic Awakening or Arks of Omen.
Watch for mentions of "The Vermin" or "The Gnaw." In Age of Sigmar, the "Gnaw" is how Skaven tunnel through reality. If that terminology starts showing up in 40k novels—specifically those written by authors like Guy Haley or Phil Kelly—then you know the rats are coming.
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Practical Steps for the Curious Hobbyist
You don't have to wait for a box set to start exploring this theme. If the idea of a verminous god in the grim dark appeals to you, there are a few ways to engage with it right now.
- Read "The End Times" and "Blightwar": Even though these are fantasy/AoS books, they define the Great Horned Rat’s personality. If he ever crosses over, this is the version we will get.
- Experiment with Kitbashing: Grab a box of Skaven Clanrats and a box of Neophyte Hybrids. The neck joints are surprisingly compatible. You can create your own "Vermin Sector" army.
- Monitor the Hrud Lore: Keep an eye on any new Kill Team releases. Kill Team is where GW tests weird new alien designs before giving them a full army. If we see a "rat-adjacent" team there, it’s a herald of things to come.
- Check the "Chaos Undivided" Updates: Sometimes minor gods are folded into the "Undivided" keyword. The Great Horned Rat might not get his own codex, but he could appear as a named entity within a broader Chaos supplement.
The reality of 40k the Great Horned Rat is that he currently lives in the "maybe" pile. He is a ghost in the machine of the setting. While he isn't an official part of the 40k lineup, the thematic echoes are everywhere. Whether he’s a literal god or just a metaphor for the rotting state of the galaxy, the Horned Rat is already scuttling through the vents of the 41st Millennium. You just have to listen for the scratching.