Koios

Koios was an obscure figure, and like most of the Titans he played no active part in Greek mythology—he appears only in lists of Titans—but was primarily important for his descendants. With his sister, "shining" Phoebe, Koios fathered two daughters, Leto and Asteria. Leto copulated with Zeus (the son of fellow Titans Kronos and Rhea) and bore Artemis and Apollo. Asteria became the mother of Hecate by Perses (son of fellow Titan Krios and half-sister Eurybia).
Given that Phoebe symbolized prophetic wisdom just as Koios represented rational intelligence, the couple may have possibly functioned together as the primal font of all knowledge in the cosmos. Along with the other Titans, Koios was overthrown by Zeus and the other Olympians in the Titanomachy. Afterwards, he and all his brothers (sans Oceanus) were imprisoned in Tartarus by Zeus. Koios, later overcome with madness, broke free from his bonds and attempted to escape his imprisonment, but was repelled by Cerberus.
Tacitus wrote that Koios was the first inhabitant of the island of Kos, which claimed to be the birthplace of his daughter Leto. Koios's name was modified from Κοῖος (Koĩos) to Κῶιος (Kō̃ios), leading to his association with the island.
Eventually Zeus freed the Titans, presumably including Koios.
However, in world Koios...