House Ærthegn

House Ærthegn is a renegade Knight House, accepted among the Imperial Knights only by Horus’s personal decree and despised by its fellows. Descendants of a long-vanished house whose world had been destroyed, they became reaver-lords. After Ullanor Horus personally tore apart the Knight of their commander on the ice seas of Altus Ferro, swore them to his Imperium and renamed them House Ærthegn — but they went on plundering worlds. They fought at the Defence of Tyros on the traitors’ side.