Quote Originally Posted by Wraith View Post
It might be more accurate to say that Chaos knows of them. They'll probably recognise the Loyalist Marines with silver armour and some seriously neat toys as something best avoided, but as to actually who they are and what their precise methods or mission statement might be? Probably not, especially given that a lot of Chaos intelligence is gathered through corruption and assimilation; no Grey Knight has ever fallen to Chaos, and no one else knows enough about the Grey Knights to be of much use.
Quote Originally Posted by Hammer of Daemons
[Chaos Lord] Venalitor snapped his fingers and a scaephylyd slave master scurried up, cradling the shoulder pad from a suit of Space Marine power armor in its front legs. Venalitor took the shoulder pad and held it up for Lord Ebondrake to see the device emblazoned across it. The ceramite was deeply carved with devotional prayers in High Gothic, and it bore the symbol of a sword thrust through an open book.
'A Grey Knight,' said Ebondrake.
'Two Grey Knights,' replied Venalitor. He looked purposefully at Arguthrax. 'Daemon hunters.'
At least some members of Chaos know who the Grey Knights are and what their purpose is.