Chronovore

The Chronovores were god-like transcendental beings who, as their name implied, fed on time itself. They were greatly feared, and sometimes respected or worshipped, because of this.

Nature
The Chronovores existed on another plane outside the universe, (PROSE: The Dark Path) and as such, they were generally uncomfortable in the universe due to the lack of physical dimensions. (PROSE: Blood Heat) They lived in the Time Vortex but ate and fed in the Six-Fold-Realm, otherwise known as Calabi-Yau Space. (PROSE: The Quantum Archangel) They could also be found in the black void surrounding the universe where it was still expanding, (PROSE: No Future) or in the Morass. (COMIC: The Crimson Hand)

The Seventh Doctor considered them the Third Law of Thermodynamics incarnate. (PROSE: Timewyrm: Genesys)

They were time sensitives like their cousins the Eternals, (PROSE: The Crystal Bucephalus) also being cousins to the Temperon, as well. (AUDIO: The Sirens of Time) However, the Guardians of Time viewed them and the Eternals as their "own children," and the Master called them the Guardians' "bastard children," the dark caste of the Chronovores being segregated at birth from the Eternal caste and consigned to exile because they failed to meet the standards of the Council of Guardians, based on their description in the Ancient Covenants. According to the council's ruling, the Chronovores were nothing but vampires: subsisting on the primal energies of the Six-Fold Realm, only truly living by drawing the life essence from the moments of choice, where they could thrive on the what-ifs and the what-might-have-beens, keeping the cosmos alone in the multiverse.

"Imagine the multiverse – the totality of all possible universes – as a garden. The multiverse has to be tended, nurtured... and pruned. Parallel universes are a fact of life – quantum uncertainties lead to Jonbar hinges and then the universe diverges, buds. But the overwhelming majority of these buds rapidly rejoin their primary universe, nanoseconds later. However, there are occasions when buds diverge from that primary reality very quickly. They possess enough dimensional momentum to achieve escape velocity – they become important. These parallel universes branching off from the primary are considered to be weeds in the garden, an infestation that must be cleared. [...] but there appears to be a possibility that they will run out of reality. [...] But these parallel realities are considered to be a threat, and, like weeds, they are pruned, weeded out. And the Chronovores are the gardeners"

- The Sixth Doctor

Like the Eternals, Chronovores were built from matrices of exotic particles, resonating superstrings that gave them power and majesty. They were living nonbaryonic matter, made from the very fabric of time itself, and in their natural form the Chronovores existed as six-dimensional polymorphic lattices of non-baryonic matter (like photinos and chronons), bound by superstrings. (PROSE: The Quantum Archangel)

They originally fed on the raw energy of stars (PROSE: The Dark Path) before evolving. Their primary food source was the Lux Aeterna, from which they gained sustenance. However, they also fed on the timelines of people (especially liking the history of a Time Lord), planets, alternate worldlines, and entire realities, timelines and parallel universes being rare feasts. As they feasted, the reality would darken and corrupt, "blossoming with the fruits of its self-destruction," which added flavour and spice to their consumption. (PROSE: The Quantum Archangel)

Appearance
Chronovores appeared as pure-white humanoids with small wings and helmet-like heads, firebirds of life and fire, but they could easily change their shapes like other transcendental beings, usually taking on feminine forms. (TV: The Time Monster) Artemis, described simply as a "bird-woman-thing", (PROSE: Conundrum) generally assumed the form of a woman in black, with black hair, red nails, and a red mouth of perfect teeth. She also wore a crown of thorns and diamonds, and manifested as a multi-dimensional mouth at one point. (PROSE: No Future) Kronos had several appearances, as a man, a woman, and something like both, and appeared as all Chronovores in order to trick the Master into thinking the entire race was after him. (PROSE: The Quantum Archangel)

Powers
In addition to their feasting on time and erasing people and things from history as a result, the Chronovores had great powers to shape reality, such as rescuing two TARDISes from a time ram. (TV: The Time Monster)

In her service to the Monk, Artemis changed events so that the Silurian Morka was able to kill the Third Doctor without the possibility of regeneration, thereby creating the Silurian Earth; (PROSE: Blood Heat) she again changed the Doctor's history so that the Garvond could come into existence; (PROSE: The Dimension Riders) she ensured Huitzilin's survival; (PROSE: The Left-Handed Hummingbird) she pulled a boy named Jason from Earth and installed him as the Master of the Land, after recreating the Land of Fiction from the ashes; (PROSE: Conundrum) and freed Varda from its time loop, enabling an invasion of 1976 Earth that never happened.

She later retroactively saved the Seventh Doctor from a fatal shot, made the Monk's mouth disappear and materialised a giant fishing hook through it, and changed history so that Ace saved Brigadier Lethbridge-Stewart's life. Because of this new timeline, Ace never set Artemis free, (PROSE: No Future) but as the Chronovores existed outside of time, they were unaffected by temporal paradoxes. Additionally, a large number of Chronovores created a natural jamming field which made TARDIS dematerialisation impossible. Kronos also created the construct Paul Kairos, a part of Kronos but also a real individual human, who was able to remove the Profane Virus of Rassilon from the Doctor's TARDIS. (PROSE: The Quantum Archangel)

In terms of weaknesses, a point-blank artron pulse from an artron cannon tore their forms, and they could become poisoned by Klypstrømic warheads that irradiated the vortex, leaving them weak and broken. But even these weapons were "small fry" to Chronovores, with vortex lances being ineffectual and Earthshock bombs being an irritation. Under the onslaught of the Eye of Harmony, their polydimensional matrices shattered and evaporated, while those caught on the edges were left broken, injured or dying. Otherwise, like the Eternals and other Transcendental Beings, the Chronovores could will themselves dead, and this was considered the only way they could die. When Kronos committed suicide, the amount of sheer energy released sent ripples through the cosmos, felt by those sensitive to time, and disrupted the space-time continuum, detonating the Great Attractor (the largest black hole in the known universe) and causing it to explode. (PROSE: The Quantum Archangel)

The blood of an Eternal was able to restrict Chronovores, suppressing their power. (PROSE: No Future)

Interaction with other races
The Chronovores were feared and hated by most other races, especially the Eternals who viewed them as parasites, uncontrollable beings of fire and ice and unutterable cruelty, (PROSE: The Quantum Archangel) and even the Third Doctor suggested Kronos to be a threat to the entire created universe, (TV: The Time Monster) the general consensus being that it was better not to attract the attention of the Chronovores to the normal universe.

More than tens of thousands of Chronovores made up the all-powerful Divine Host, the shock troops of the race. Only a few Chronovores roamed the universe at any time, spotting the few alternate timelines as they formed and devouring them, as they were unable to enter what they called the "Higher Place" (the space-time continuum) unless they were summoned. According to the Ancient Covenants that governed them, once a link was forged between two regions, either spatial, temporal, dimensional, or otherwise, the Chronovores were free to pass between them. (PROSE: The Quantum Archangel) They were summoned through rituals, one in particular that involved a pentangle with the blood of five races whose genetic destinies had been altered by the Capitol on Gallifrey: Minyan, Silurian, Dalek, Human, and Mandrel. A Chronovore would consume the blood, making an image of the being appear and move around the pentangle as it grew older and died. Artemis commented that it was always the "same races." (PROSE: No Future)

Not being "normal life" or existing in the universe, concepts like "pain" and "obey" (PROSE: Blood Heat) were not understandable. Neither were the concepts of using metaphors or a language or having a personality, and Artemis was content to eating Earth and every human as they had such short lives anyway before the Doctor convinced her she had a merciful personality. She did find mortals could be entertaining. For freeing her, however, she willingly granted Ace a wish.

She warned the Seventh Doctor to never tell a Chronovore to 'stop' as it annoyed them. She, if not all Chronovores, thought it laughable that Time Lords felt they owned Time, like how fish thought they owned water; she stated that fish at least could feign ignorance as they had never heard of fishermen. (PROSE: No Future)

History
The ancestors of the Chronovores originally lived in the normal universe, able to move across time as other species moved across space. In the event that one of their kind grew tired or became ill and were stranded somewhere at some time, they built the Darkheart, a space/time conduit and medical device, to transmit energy to any point in space and time. They eventually evolved into a higher plane outside of time, (PROSE: The Dark Path) although another account claimed they were spawned by the Great Old Ones and were billions of years old. (PROSE: The Quantum Archangel) Breaking the Ancient Covenants, the Eternal Elektra and the Chronovore Prometheus conceived a child, Avatar, and were confronted by the Guardians as the Six-Fold-God in the darker strata, deep within the time vortex. Prometheus's existence was undone and Elektra was taken away, the darker strata being shunned and disowned and wiped from the collective memories of both races because of the horror and collective shame of summoning the Six-Fold-God. Later, Lillith, matriarch of the Chronovores, petitioned for the Avatar to be destroyed, but the God spun a crystal and imprisoned the Avatar, which would later be known as Kronos. The crystal appeared on many worlds, eventually arriving on Dæmos before the Dæmons brought it to Atlantis on Earth. Although used benevolently and worshipped, when the Master accessed the crystal in an encounter with the Third Doctor, Kronos was released earlier than intended and went mad, destroying Atlantis. (TV: The Time Monster, PROSE: The Quantum Archangel)

Two Chronovores roamed the Vortex while Ramón Salamander was drifting through time towards Earth. (COMIC: The Heralds of Destruction)

In 2003, as revenge against the Chronovores, Kronos tricked the Master into cutting off the Lux Aeterna. However, in the process the Quantum Archangel was born and, in an effort to give all seven billion people on Earth their ideal reality, she created seven billion parallel universes around the planet. As this was their only food, the Chronovores swarmed the Earth and began feeding slowly, acting like parasites and not carnivores so as to prolong the feast for eternity. Working with the Sixth Doctor, Kronos sacrificed himself and detonated the Great Attractor, giving the Lux Aeterna a way home and allowing the Chronovores back into the Six-Fold-Realm. (PROSE: The Quantum Archangel)

The Chronovores were present at the Timewyrm's creation, bestowing the name upon her. (PROSE:  Timewyrm: Genesys)

later enslaved the Chronovore Artemis to get revenge on the Doctor, after which Artemis was freed and took her revenge on Mortimus for imprisoning her. (PROSE: No Future)

Behind the scenes

 * The Chronovores were due to return in AUDIO: The Avenues of Possibility, but were dropped in pre-production. (DCOM: The Legacy of Time: Behind the Scenes)

Cronívoros