Sith Covenant

Descended from a long line of Sith, the Covenant considers themselves the only true heirs to the Sith legacy.

History
Darth Bane was not the only one to continue after the last battle at Ruusan. Unknown to everyone else, another Sith Lord, Darth Martal, had survived the destruction of the Brotherhood of Darkness.

Unlike Bane, Martal had no interest in overthrowing the Republic. In his view, it was better to control the galaxy behind the scenes than to take overt control as Palpatine eventually did. Instead, Martal created an organization based on stealth backed by unlimited power.

As a result, the members of the Sith Covenant became masters at stealth. Even at the height of the Galactic Empire, the abilities of the Covenant ensured that Palpatine's Force-user hunters never found - or even sensed - them.

Finally, in 17 ABY, the Covenant began to expand their covert rule to the planets surrounding Roon, their ancestral haunt. With the amount of Sith appearing in the Galaxy, the current Dark Lord of the Sith, Darth Obscurus, resolved to expand his powerbase for the seemingly inevitable clash with the other Sith groups - the Sith Order, the Sith Brotherhood and the Cult of Shadow...

Hierarchy
The Dark Lord of the Sith is the master of the Covenant, and rules supreme. He is necessarily the most powerful of all the Sith, as he would otherwise quickly be replaced by one of his apprentices. The Dark Lord of the Sith usually takes on a unique name preceded by Darth (ie, Darth Obscurus).
 * Dark Lord of the Sith

Sith Lords are the most powerful Sith (excluding the Dark Lord, of course), and usually has an apprentice serving beneath them. Like the Dark Lord, Sith Lords usually takes on a unique name preceded by Darth (ie, Darth Kabal).
 * Sith Lord

The Shadow Hands are the most able servants of the Dark Lord of the Sith, trained and existing only to carry out his will. They take only his orders, and reports only to him. Like the Dark Lord and Sith Masters, a Shadow Hand usually takes on a unique name preceded by Darth (ie, Darth Vheil).
 * Shadow Hand

Similar to Jedi Knights, Sith Knights are Sith who have completed their training as Sith Apprentices and may now take their own Apprentices. Knights are not allowed to use the Darth prefix.
 * Sith Knights

Sith Apprentices are former Blackguards chosen to study under the tutelage of a more experienced Sith Knight or Lord. At this point, they are considered Sith, though they are still expendable.
 * Sith Apprentice

Technically not Sith, Blackguards are Dark Jedi who serve as low-level operatives and foot soldiers. They are considered expendable by the true Sith, and rarely know who their true masters are.
 * Blackguard

Neophytes are technically not Sith. Rather, they are Force-sensitives chosen by the Sith and trained as Dark Jedi. If they survive the harsh training, they will eventually be promoted to Blackguards, and may some day become Sith Apprentices or Shadow Hands. Neophytes rarely realize that their masters are Sith, as they never identify themselves as such. Neophytes are not allowed to leave Roon.
 * Neophyte

Despite appearances, the Covenant remains a small organization, numbering less than 10 Sith. Few outside those 10 know that the Covenant exist.

Chain of Command
Neophyte => Blackguard => Sith Apprentice => Sith Knight => Shadow Hand => Sith Master => Dark Lord of the Sith

Locations

 * Roon - The headquarters of the Covenant are located here, as are the Neophyte training grounds. Only those of Knight level and above know the location of the Citadel.

Dark Lord of the Sith

 * Darth Obscurus

Sith Lords

 * Darth Kabal
 * Darth Invide

Shadow Hands

 * Darth Vheil
 * Darth Attera

Sith Apprentices

 * Kornil Vraen
 * Daros Cairn
 * Tol Reban

Blackguards

 * Balor Vane
 * Nimas Kord
 * Sira'lja
 * Sienna Torr
 * Torquis Kwir
 * Nianna Borr
 * Sin Mai
 * Kria Dokus

Neophytes

 * Katya

Philosophy
The philosophy of the Covenant is based on stealth backed by unlimited power. The Covenant prefers to act through unknowing henchmen, and eliminates everyone who learns of their existence.

Even so, the ultimate goal of the Covenant is unknown to all but Darth Obscurus.

The Code of the Sith

 * Peace is a lie, there is only passion.
 * Through passion, I gain strength.
 * Through strength, I gain power.
 * Through power, I gain victory.
 * Through victory, my chains are broken.
 * The Force shall set me free.

Credits
Parts of this text have been copied from Wookieepedia