Kotturuh

The Kotturuh, or the "Bringers of Death", were a species from the Dark Times who could bring an end or apply a limit to the lifespan of other species. (PROSE: The Guide to the Dark Times)

Biology
The Kotturuh were immortal, with the ability to grant (or enforce) a defined lifespan upon an entire species - from thousands of years to instant destruction. They typically wore robes which concealed their tentacled lower halves. (PROSE: The Guide to the Dark Times, et al.)

The Kotturuh had purple skin. (PROSE: The Knight, The Fool and The Dead)

Culture
The Kotturuh saw death as both their religion and their gift to other species. (PROSE: The Guide to the Dark Times) They referred to this as their "Great Task". (PROSE: The Dawn of the Kotturuh)

When the Doctor was planning on blowing up the Ark of Whispers to prevent it from crashing into a planet, Benny mentioned the Rites of the Kotturuh as a piece that may be aboard the mythical ship. (AUDIO: Have I Told You Lately?)

Kotturuh individuals wore robes adorned with symbols each taken from a different civilisation they had judged. (AUDIO: Lesser Evils) The Tenth Doctor noted these symbols seemed to shift as he tried to take them in. (PROSE: The Knight, The Fool and The Dead)

History
The Kotturuh believed that they had been spreading the "gift" of death in the universes before N-Space and that they would continue to do so in the subsequent universes. (PROSE: The Dawn of the Kotturuh)

The Kotturuh were among the first species in the universe. After a while, they set out to distribute death among the denizens of N-Space. (PROSE: The Guide to the Dark Times) This began on the planet Birinji, where a triumvirate of Kotturuh assessed the native population as contributing little to the Great Song and accordingly assigned them a lifespan of three months. (PROSE: The Dawn of the Kotturuh)

They were known to either visit worlds peacefully, before allocating lifespans to the natives of that world, or else they would simply destroy life on a planet without so much as a word.

Many species attempted to flee from the Kotturuh, such as the Eternals, who sacrificed their ability to lead their own lives in the process, hence their reliance on Ephemerals. The Racnoss, meanwhile, went into hibernation to avoid their destruction.

Other species attempted to negotiate - the Osiran Sutekh bargained with the Kotturuh for the gift of death; the Great Vampires managed to keep their immortality on the one condition that they must feed on others to sustain their existence.

The Dæmons tried to fight back, but the Kotturuh were too powerful, leaving only Azal, who fled to Earth to live in suspended animation.

Later, the "Kotturuh crisis", as it was termed by journalist Melody Malone, was a rising threat in the universe. It involved the Doctor and the Dalek Empire. (PROSE: The Guide to the Dark Times)