The Five Hundred Worlds is the grand name for Ultramar, the interstellar realm built by Roboute Guilliman. It’s the biggest human domain outside the Imperium proper, and right now it’s the setting for a massive reclamation war.
What the Five Hundred Worlds actually are
Ultramar is a cluster of roughly five hundred planets, though the exact number has shifted over ten thousand years. Guilliman designed it as a self-sufficient mini-empire: each world contributes troops, resources, and ships, and the whole thing is defended by the Ultramarines and their auxiliaries.
That independence is why it matters. While the rest of the Imperium decays, Ultramar mostly works. It’s a proof of concept for good governance in a galaxy that’s forgotten how.
Why they’re in the spotlight now
After the Great Rift tore the galaxy apart, Guilliman returned and turned his attention back to his old realm. But the Five Hundred Worlds had been badly hit. In the 500 Worlds: Titus campaign, he tasks Captain Demetrian Titus with reclaiming them.
The first target is Novamagnor, a blighted world where a new Necron threat has emerged. Titus has to beat Nekrosor Ammentar, a horrifying entity even other Necrons fear, along with its Destroyer legions and shards of the Nightbringer.
- Guilliman ordered the reclamation after the Great Rift.
- Titus is Captain of the Ultramarines 2nd Company again.
- The campaign begins on Novamagnor against Necrons.
The 500 Worlds: Titus campaign book
This is a boxed campaign set for the 10th edition of Warhammer 40,000, released in January 2026. It’s the first chapter of a larger story arc about retaking Ultramar.
Inside you get three books, a booklet, a fold-out map of the Vespator Front, and a sticker sheet for tracking progress. It supports both narrative and matched play.
| Component | What it covers |
|---|---|
| 500 Worlds: Titus | 80-page lore and background of the opening moves |
| Dread Incursions | 80-page boarding actions rules, 12 missions, 2 detachments |
| War on the Vespator Front | 56-page narrative campaign with 6 missions |
| Detachments booklet | 16 pages, 3 new detachments each for Marines and Necrons |
| Extras | Fold-out map (594x420mm) and 252-sticker progress sheet |
Key figures and forces
Titus leads from the front, supported by a close circle that includes Veteran Sergeant Metaurus, Ancient Gadriel, and a plenipotentiary of Ultramar named Lucia Vestha. The fleet and auxilia are represented by Commodore Gaius Silva and Legatus Aemelia Minervas.
Against them stands Nekrosor Ammentar, a being so twisted that even the Necrons dread it. It commands Destroyer cults and C’tan shards, including the Nightbringer, whose gaze can drain life and whose scythe cuts down swathes of foes.
How it connects to wider lore
The Five Hundred Worlds have always been the Ultramarines’ backyard, but they’re more than that. They’re Guilliman’s attempt to build something better than the Imperium’s rotting bureaucracy, and their survival matters to the whole setting.
The reclamation ties directly into the aftermath of the Great Rift and Guilliman’s return. It also sets up a new Necron antagonist in Nekrosor Ammentar, so expect this story to keep growing.
Key facts
- The Five Hundred Worlds is another name for Ultramar, Guilliman’s realm.
- It’s a self-sufficient empire of roughly 500 planets, defended by the Ultramarines.
- Guilliman ordered its reclamation after the Great Rift.
- Captain Titus leads the effort, starting with the world of Novamagnor.
- The 500 Worlds: Titus campaign box launched in January 2026 for 10th edition.
- The main enemy is Nekrosor Ammentar, a Necron horror commanding Destroyers and C’tan shards.
FAQ
Are there exactly 500 worlds in Ultramar?
No, the number is more of a title. It’s traditionally around five hundred, but the actual count has changed over time and some worlds have been lost or gained.
What is 500 Worlds: Titus?
It’s a campaign box for Warhammer 40,000 10th edition, released in January 2026. It kicks off a new story arc about reclaiming Ultramar from a Necron threat.
Who is Nekrosor Ammentar?
A terrifying Necron entity that even other Necrons fear. It’s invading Ultramar with Destroyer legions and C’tan shards, and it’s the main villain of the first 500 Worlds campaign.