Clans are the largest organisational unit in the Dark Brotherhood, consisting of up to three (3) Houses, each House can either be aligned to a single Order and thus only have members from that order, or they can be Multiorder Houses in which members come from all three orders.
Clans are led by a Clan Summit, consisting of a Consul, the primary command position, and the Proconsul, the secondary command role. The Clan Summit is the highest possible position in the Brotherhood without sitting on the Dark Council, and as such, the highest levels of professionalism are expected from persons holding these positions.
The Clan Summit is responsible for the cohesive operation of all three Houses and their Battleteams. Clans are unique from other units such as Houses in that they feature in a special type of Vendetta - the Clan Feud.
In a Clan Feud, two Clans compete for the ownership of possessions. These possessions are usually acquired previously in other Vendettas, such as a Great Jedi War. Clans can also hold titles, similar to Houses, for placing in a Rite of Supremacy, such as "First Clan", "Second Clan" and so on. These titles are held for the duration between Rites and the use is discontinued upon another Clan holding that place.
The clans are Arcona, Naga Sadow, Plagueis, Scholae Palatinae, Taldryan, and Tarentum. The Dark Council is sometimes called the 'Over-clan' of the brotherhood, but this term is relatively archaic.