Kronos

Kronos, also spelt Cronus, was the most fearsome of the Chronovores, a species of extradimensional creatures that devoured time. He and his siblings were worshipped as Titans by the ancient Greeks, (PROSE: The End Times) and by the people of Atlantis, which he eventually destroyed. He was revered as "Rhea's husband, Gaia's saviour, father-slayer, child-eater, Lord of the Golden Age." (PROSE: Fallen Gods) Rhea's destructive husband was known in other sources as Saturn. (PROSE: The Best of Days) During an encounter with the Third Doctor, Kronos described themself as "a destroyer, a healer, a creator ... beyond good and evil", and claimed to have known the Doctor "of old". (TV: The Time Monster)

Origins
The gods' early ancestry was confused, but certainly involved the primordial entity Chaos, the goddess Gaia, Gaia's daughter Tethys, or Tethys's daughter Euronyme. The later gods did not know their own early genealogy, but suspected they had forgotten certain details for good reason. Their genealogy also tended to change over time, so gods sometimes had multiple contradictory relationships. (PROSE: Wandering Stars)

In the mythology known to the Greeks, Cronus was a son of Gaia, and killed his own father to save her. Later, Cronus married Rhea, who bore him several children, each of whom he swallowed at birth. Rhea hid their last son, Zeus, instead feeding Cronus a stone in swaddling clothes. (PROSE: The End Times) Rhea and her children eventually cast Cronus into Tartarus. (PROSE: Fallen Gods)

The Eighth Doctor believed that the Titans had descended from tiny creatures which lived in the deep sea by the volcano on the Greek island Thera. Unable to evolve normally in this hot, dark, heavy environment, they instead evolved an ability to move through time. Most sailed out into the time vortex, but a few, amused by humanity, chose to remain; and then someone, either human or Titan, found a way to bind them to the volcano. (PROSE: Fallen Gods)

By another account, Kronos was the offspring of a Chronovore known as Prometheus and an Eternal known as Elektra, a union which violated the Ancient Covenant. (PROSE: The Quantum Archangel) At the moment of his birth, Kronos was imprisoned in a crystal and was cast down to the Ephemeral universe. Eventually, the crystal landed on the planet of the Constructors of Destiny, where he influenced their culture and became a godlike figure. Over billions of years, the crystal was hidden on millions of planets, including Skaro and the world of the Dæmons. The Dæmons then sent the crystal to Atlantis on Earth, so it could destroy it, because the Dæmons deemed it a failed experiment. (PROSE: The Quantum Archangel)

Worship on Earth
In Greek mythology, Kronos was the Titan who ate his own children, including Poseidon, but was eventually overthrown and supplanted by his son Zeus. (TV: The Time Monster) These stories, "in some brainmelting timeless way", were actually true, and reflected a struggle between primal, extradimensional forces. (PROSE: The End Times) Zeus performed some unknown act on Kronos, causing time to "run wild and free". (PROSE: Wandering Stars)

Kronos was worshipped in Greece and on the island of Atlantis, for a prosperous age referred to as the "golden years". (TV: The Time Monster) In reality, Atlantis's wealth came from their priests' mastery over Kronos and his Titan siblings, who were imprisoned in the pit of Tartarus. Eventually, around 2000 BC, the Atlanteans overstepped, and the Titans devastated the Aegean Sea with volcanoes and earthquakes. (PROSE: The End Times) Dalios, who witnessed the destruction as a young man, lived for another five hundred years, and mocked younger Atlanteans who longed for Kronos to return. (TV: The Time Monster)

After his downfall, Saturn spent centuries recovering his power. In the 1st century BC, he possessed a statue of himself during Saturnalia, grew it to gigantic size, and attempted to incite Roman slaves to rebellion. Rhea, now in the form of a little girl, gave Ace a stone and the Seventh Doctor a bottle of poison, each to throw at him. When the stone and poison reacted, the statue returned to its original size, and Saturn was vanquished. Rhea was unable to harm Saturn directly because of her marriage vows. (PROSE: The Best of Days)



Fall of Atlantis
In the 1970s, gained possession of a fragment of the crystal, and used it to summon Kronos so as to enslave him. This failed and the Master went back in time to the last days of Atlantis. Kronos ruined the city. In the aftermath, he stopped both the Doctor's and the Master's TARDIS in the Time Vortex and, appearing as a huge, translucent female face, asked the Third Doctor whether he wanted Kronos to destroy the Master. The Doctor demurred, Kronos let him free, and the Master escaped into his TARDIS. (TV: The Time Monster)

Quantum Archangel crisis
During the Quantum Archangel crisis, Kronos created the persona of Paul Kairos, a student under Ruth Ingram and Stuart Hyde, to manifest upon Earth. Kairos, through miraculous talent, had reverse-engineered the Master's TOMTIT device, and created an enhanced version, the TITAN Array. He was stripped of the rights to his own invention, the quantum lattice, by Anjeliqua Whitefriar, and was in a relationship with a fellow student, Arlene Cole.

As Kairos, Kronos worked with the Sixth Doctor and helped end the crisis by shedding his human guise and attacking the Mad Mind of Bophemeral during a violent engagement between the Archangel and the Doctor. Following this, he allowed the Kairos persona to remain active as an independent being, but not before Kronos was forced to sacrifice his life in order to destroy the Mad Mind. (PROSE: The Quantum Archangel)

Appearance
When briefly released from the crystal, Kronos appeared as a brilliantly luminous white figure, approximately humanoid in shape but with large, cloth-like wings in place of arms. His skin was smooth, rigid and armour-like, and his head resembled a vaguely avian helmet.

When the crystal was finally destroyed, Kronos assumed the gigantic form of a woman's face, with glittering golden eyeshadow. Kronos explained that he could change his appearance freely: "Shapes mean nothing." (TV: The Time Monster)

As Professor Paul Kairos, Kronos appeared to be a chubby Greek man in his late thirties with olive-coloured skin, short hair, and a goatee. (PROSE: The Quantum Archangel)

Behind the scenes

 * The name Kronos refers back to Greek mythology; was the father of the Olympian Gods.
 * The Titan Cronus (Kronos) has been conflated with, the Greek embodiment of time.