Dark Lord of the Sith - The unquestioned ruler and leader of the Sith. The Dark Lord alternatly serves as the Sith Emperor as well.
Darth - An unofficial "rank", the title of Darth is granted to a Sith upon acension to the Dark Council, or upon outstanding Sith. Upon receiving the title of Darth, one assumes a new name, unique to themselves, often based upon their personality and accomplishments.
Sith Lord - A Sith Warrior who has returned from their conquests and have earned the right to train an Adept. In order for preservation of numbers, Sith Lords are not required to kill their former Master, unless the Master wishes for this final test of their Apprentice. It is, however, compulsory for any Dark Councilor to be replaced by a duel to the death. They are alternatively known as Sith Masters.
Sith Warrior - A Sith no longer with a Master, but without an Apprentice. They make up the bulk of the Sith. While it is rare, there are Warriors that
take on Acoltytes as their apprentice, although most do not do more than
train Adepts until reaching the rank of Master.
Sith Acolyte - A Sith Adept which has earned a Master of their own, also known as an Apprentice.
Sith Adept - A Sith which has begun their training within the Sith Academy. They fill a role largely once known to be of Dark Jedi; those who do not earn a Master, but survive their training, stay Adepts for the rest of their life, but are utilized as free-roaming agents of Sith Lords. Although it is extremely rare, these particular Adepts, should they prove themselves, may earn the position of Acolyte.
Sith Minion - The de dacto rank within the One Sith for any non-Force sensitive servant. In the current Sith Order, any Dark Jed unworthy, or unwilling, to attempt to become a Sith, are deemed such.