The Warhammer 40,000 universe is not for the faint of heart. With various xenos armies and the heretical forces of chaos fighting the Imperium for control of the galactic expanse, there aren’t many safe places to earn a living in the far future.
However, some of the planets in the 42nd millennium are deadlier than others. Countless humans die each day as fuel in one way or another for the Imperium’s way of life. Whether it’s life as they know it, natural dangers, or the ever-present threat of war on the horizon, these are by far the deadliest planets in the Warhammer 40k universe.
Spoilers follow for various books, games, and other 40k media.
Catachan
A Death World Indeed
Catachan is a planet used as the setting of various books and other lore and is marketed as deadly on purpose. You know, in a universe like 40k, when something is classified as a Death World, that it’s far worse than you could ever imagine. Catachan is one of these Death Worlds, known as such because every facet of life there is deadly to humans.
The weather, geography, flora, and even fauna are all more than capable and happy to kill anything that gets too close. The good news is that those who survive the hostile nature of the planet are some of the toughest citizens of the Imperium, especially those who join their guard unit, the Catachan Jungle Fighters.
Necromunda
Hives As Far As The Eye Can See
Necromunda is a planet that has worked as the setting of many a board game, book, and now a few video games. It’s a hive planet that has made itself known over the years of lore for being particularly gruesome. Cities miles tall and spanning continents are the only real bastion for humanity outside or irradiated deserts of dust.
Inside these cities, the rich live in opulence in the tallest towers, but the everyday citizen of Necromunda deals with gangs, tyrannical police and rulers, and the ever-present threat of mutation and chaos cults. There’s also the unfortunate understanding that the factory work common in these cities as forms of employment will likely maim you.
Terra
Where It All Began
A controversial statement, but the holy planet of Terra (Earth) is far from the cradle of humanity that it once was. Seas boiled dry, mountains leveled, the entire planet is now one large hive city.
While it is easily the most protected planet in the Imperium, death isn’t far away for any citizen of Terra. The sprawl and crush of other people means resources are limited, disease is common, and workplace injuries are too. Not to mention, there is a giant target on Terra at all times from any army warring against the Imperium, which includes all of them.
Armageddon
Orks, Tyranids, Chaos,
Armageddon has been through the wringer far more than once. It does host one of the deadliest and most stoic of the imperial guard regiments, the Armageddon Steel Legion, but it’s easy to see how someone growing up there would have to get tough fast.
There are hive cities and radiation plains like in some other planets on this list, but the real standout is the constant war. The planet has seen an invasion of tyranids, an Ork Waaagh, and a Chaos incursion, some at the same time. There are multiple Wars for Armageddon on the timeline, and they don’t seem to be ending any time soon.
Kronus
Gripped By War
The planet that is the setting for the Dawn of War games, Kronus has seen it all. It isn’t terribly unusual for a particularly important planet in the galaxy to be contested over by multiple factions in 40K, but Kronus takes that to a whole new level.
The planet is held by the Imperium by the mysterious Blood Ravens chapter of space marines and various human forces. They have fought a war against Eldar, Ork, Word Bearers, and T’au. It is later revealed that it is also a Necron tomb world. If there was ever a planet to avoid, this is pretty up there.
Isstvan III
Legacy Of Betrayal
Many planets in the 40K universe have long and rough pasts. Not all have made it into the ‘current’ timeline. Isstvan III was an altogether normal-ish world in the 30K timeline and played a pivotal part in the events of the Horus Heresy.
It was the Isstvan system where Horus and the first of the traitor legions attacked their brothers en masse. This assault was in part carried out by various virus bombs dropped on the planet’s surface. The results of which make it impossible for anything biological to survive on the planet at all.
Fenris
Long In The Tooth
The home world of the Space Wolves legion of space marines, Fenris is at least in part why this chapter is so fearsome. The temperatures of this arctic planet are far below hospitable, and the tribes that live there do so with only the basic amount of resources, often choosing to raid other neighbors for survival.
Included in this are the giant wolves that hunt the land and the krakens that call the seas and lakes their home. Post-heresy, it has become a target for the Thousand Sons, eager to enact revenge for their own planet being leveled.
Cadia
Cadia Stands?
Cadia is a planet in a pretty perilous position—and one that met an untimely end. While it was still a planet, Cadia was on the edge of the Eye of Terror, the place where the warp enters real space. It was revealed that the planet and its inhabitants were more resilient to warp energies, making them a sort of bulwark against chaos incursions. That is a rough spot to be in, regardless of the new timeline.
While many had tried, Abaddon finally cracked the planet and opened the Eye further. Asteroids still exist where survivors have set up training grounds and try to hold their own, but it isn’t the pride and joy of the Imperium that it once was. At least the planet broke before the guard did.