The tau are a relatively new race in the WK40K, the Necron are an ancient one. According to the 6th edition wargame rule book allies table, Tau and Necron forces are 'Allies of Convenience'.

Necron fluff has supposedly changed (in sixth edition) so they don't have to be merciless killing machines.

Is there anywhere in cannon that shows they've allied or opposed each other? Either in the snippets of fluff or the various novel for the WH40K universe?

When I looked on Google I found forum posts saying may had happened, and was mentioned in a codex somewhere.

  • Not familiar with any 40K books, but I've read codexes and tons of material online. I'd like to know how the Necron, who oppose all living things, could be considered "allies of convenience" with the Tau, who are living things :P I think the Allies from 6th edition make sense gameplay-wise, but breaks all sorts of fluff...
    – Andres F.
    Commented Aug 23, 2012 at 2:31
  • @AndresF. because the Tyranids are worse
    – OrangeDog
    Commented Dec 7, 2021 at 17:05
  • @OrangeDog In which sense? The Tyranids want to devour all life and incorporate it to their biomass, while the Necrons want to extinguish all life. How are Necrons better? :)
    – Andres F.
    Commented Dec 7, 2021 at 18:04
  • @AndresF. The Necrons know they will lose to the Tyranids by themselves. They have to ally up to survive, and then can kill their allies later.
    – OrangeDog
    Commented Dec 9, 2021 at 11:03

5 Answers 5


Yes they have on Cano'var 813.M41:

At Nemosar Zahndrekh's instruction the armies of Gidrim invade the Tau world of Cano'var, routing the planetary defender's after two weeks of campaigning.

From the Necron Codex.

This is not their only encounter however. For more encounters with necrons, see this timeline.

As for allying, the new fluff for the Necron's opens up the possibility for peaceful relations with other races. There are accounts in the same codex of them giving various items to other races for truces, though one of these incidents resulted in the self-destruction of a planet.

  • 2
    An alliance of convenience is very far from "peace". It just means since A hates C more than B, A will refrain from killing B while B are currently killing C (and vice-versa). Once the current battle is over, its right back to killing each other.
    – OrangeDog
    Commented Jan 8, 2021 at 11:31

Besides crackpot theories that Tau are Necrontyr somehow, and the not-necessarily-canon Dawn of War games, no specific examples. Google doesn't yield much, either. However, it's accepted that there are Tomb Worlds all around the galaxy, including, presumably, in and around Tau space.

As for whether or not they'd fight each other - of course. Necrons fight against all life. They would shoot the Tau as soon as possible, never mind after hearing their "Greater Good" pitch.

As for whether they'd fight alongside them - sure. If they're fighting against Psykers or latently-psychic species, the Necrons probably still regard psychic powers as high-priority targets from the wars against the Old Ones, the Eldar, and the Orks. Otherwise - who knows? Their force might have done something, obvious to us or not, that the Necrons regard as more threatening, giving that faction target priority. Or maybe your Necron Lord is particularly capricious or bored.

  • 1
    Refer to PureFerret's answer; this was the strongest speculation until he gave the canonical (i.e. correct) answer.
    – rsegal
    Commented Jul 8, 2013 at 3:04

I am fairly sure that there is a snippit within the tyranids codex timeline.

The Tau were getting hammered by Tyranids that had become immune to their Ion weapons. Then suddenly Necrons show up and wipe out the Tyranids in short order. The Tau then try to show their gratitude and welcome the Necrons to the planet.

The Necrons kill the Tau...


I don't know if you consider this a worthwhile source, but in the Dawn of War: Dark Crusade game, the Tau and Necrons are opponents. The Tau are attempting to cleanse Kronus "for the greater good", while the Necrons are on one of their "merciful" killing sprees.


Anrakyr the Traveler, a nomadic Necron Overlord, has a cool story where he cleanses a Tau planet on a Tomb World after he saved them from Tyranids.

I am not capricious, nor am I given to cruel acts for their own sakes. It is simply a fact that you and your kind have trespassed, and thus invited extermination. Curse you for putting me to this inconvenience."
—Anrakyr the Traveller to the T'au Ethereal Aun'taniel prior to the Harvest of Ka'mais

Ka´mais was the Tomb World and attacked by Tyranids.


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