The Skaven are socially organised into many feuding clans, each vying for ultimate supremacy over the Skaven under-empire. Of these, there are four greater clans: Clan Skryre, the engineers, Clan Pestilens, the plague bringers, Clan Moulder, the flesh moulders, and Clan Eshin, the nightlords. After these four giants are the warlord clans, of which the most notable is Clan Mors. The warlord clans often ally themselves to one of the major clans for influence and protection, with some ending up in the thrall of one of the big four. As well as the warlord clans there are countless many smaller, less significant clans, some even without name, these are collectively known as the multitudinous or rabble clans.