The Great Companies are the twelve primary organizational units of the Space Wolves, analagous to a Company in another Chapter. In defiance of the Codex Astartes, which dictated the reorganization of the Adeptus Astartes after the Horus Heresy, the Space Wolves Chapter has twelve companies instead of ten[1a].
Character and Organization
Each Great Company is responsible for its own recruitment, maintenance, and running, each acting as a separate force altogether, each lead by a Wolf Lord in a semi-feudal system. The Wolf Lord of the leading Great Company is also the Great Wolf, the Chapter Master of the Space Wolves[1a].
The 13th Company
There was once a 13th Great Company, and rumors still abound as to the reason for its disappearance[1b]. Some state that they disappeared into the Warp during the attack on Prospero, the traitorous Thousand Sons' homeworld; others claim they disappeared after the Primarch Leman Russ himself went missing. Regardless, there is currently hardly any information concerning the company in the Imperial records.[Needs Citation]