Dark Ones

The Dark Ones, or Clan of Darkness in the English dub version, are a clan of Shinigami that were exiled over 1000 years ago. The name of their clan was the Fallen House of Ryōdoji, though the Dark One's leader no longer claims ties to that name. They took refuge in the Dangai Precipice World and later in the Valley of Screams. Their leader, Ganryū, planned revenge against the Soul Society by finding the Shinenju and using it to collide Soul Society with the Human World, destroying them. The Dark Ones were defeated by Ichigo Kurosaki, Senna, and various members of the Gotei 13.

History
The Dark Ones were actually once known as The House of Ryōdoji, but Soul Society exiled them 1000 years ago for unknown causes. Amazingly, the group somehow managed to avoid the deadly current flowing through the entire Dangai, and resided there for many years. It was in this world that the clan of exiles discovered the souls that evaded transmigration and turned into wandering ghosts: The Blanks. The Dark Ones learned to harness the Blanks as an energy source for their own power. The Dark Ones learned all the information there is about Blanks and the Valley of Screams, which they chose to reside in, and formulated a plan for revenge against Soul Society.

Hierarchy
The Clan of Darkness is made up of six members including Ganryū the leader who also calls himself the "Dark One" in the English dub movie. The other five include four men and one woman all of whom were soundly defeated by the Shinigami. The members names are as follows:

Leader
Ganryū was the leader of the Dark Ones, due to his ingenuity and power. Killed by Ichigo Kurosaki after a long battle.

Subordinates
Jai - A dark-skinned member of the clan. He was killed by Byakuya Kuchiki.

Benin - The only female of the clan, she was killed by Soifon.

Riyan - Member of the clan with what appears to be two rocket packs on his back. He was killed by Tōshirō Hitsugaya.

Bau - A large man having his face completely covered by a veil and caring two large weapons. He was killed by Renji Abarai.

Mue - A small, pale clan member who liked to attack from a distance. He is killed by Kenpachi Zaraki.

Allies
Blanks - The entire race of Blanks was used solely for their own ambition. Not one Blank showed any originality from the rest, but were used creatively by the Dark Ones.

Powers and Abilities
While it is not known if the clan wielded Zanpakutō or just had unusual weapons as it was never stated, they all displayed unique powers involving the Blanks. Apparently they could use the blank souls to replenish their weapons, create new ones and even regrow limbs.

Teamwork Experience/Strength: The group was very powerful, as shown when despite the presence of three Division Captains, their plan to kidnap the Memory Rosary went perfectly.

Skilled Strategists: They were also very insightful, as seen afterward when they used an escape route planned beforehand to evade the Gotei 13 completely.

Blank Control: The Dark Ones eventually learned how to harness the Blanks for their own power, during the time they spent in the Dangai Precipice World. They also had the Blanks do their bidding in the Valley of Screams, ordering them to fuse around the Memory Rosary creating a gigantic cocoon-like structure. Blanks were used to augment their weapons

Expert Weapon Specialists: The Clan members were highly skilled in their respective weapons, able to make three Division Captains ineffective against their kidnapping attempt.