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. 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.

Members
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. They also had the Blanks do their bidding in the Valley of Screams, ordering the to fuse around Senna creating a gigantic cocoon-like structure.

How they gained this ability was also never explained.