Ouranos

"If you do this, Kronos, I will curse you! Someday your own children will destroy you and take your throne, just as you are doing to me!"

- Ouranos to his son Kronos

Ouranos is the Greek personification of the sky; he is one of the Protogenoi, or "first born" - the first beings to have sprung from the void of Chaos. Ouranos is the Greek word for sky, and his Roman counterpart is Caelus. The Greeks imagined the sky as a solid dome of brass whose edges descended to rest on the outermost edges of the earth. He was the husband of Gaea, and he fathered the Titans with her before being conquered by his son, Kronos.

History
Ouranos and Gaea were the protogenoi of the sky and the earth respectively. They became consorts and brought forth their children: the Cyclopes, the Hekatonkheires, and the Titans.

Ouranos didn't care for his children at all. In fact, he hated them. He hated those of his children that did not look normal most of all, such as the Hekatonkheireres and Elder Cyclopes. They were unsightly in his opinion and he wanted them gone. But he couldn't kill them because they were immortal, like him.

So instead, Ouranos chained all six of them up with extremely durable black chains (forged from the darkness of the night sky) and subsequently hurled them into Tartarus. This caused Gaea great grief. She was also furious because they were her children, and Ouranos cared nothing for them. Having forged a scythe, she then gathered her remaining children, the Titans, requesting them to take it in order to get rid of Ouranos and free their brothers, the Cyclopes and the Hekatonkheires. The Titans were scared of their father as he hurled the Cyclops and Hekatonkheries to Tartarus.But the youngest Titan wanted to show his bravery to the others as he being the smallest couldn't show it.So Kronos agreed to Gaea and he brain washed his brothers to help him. The first betrayal hadn't occurred yet, Ouranos was oblivious to his wife's plans. Kronos took the flint scythe Gaea made and castrated his father before cutting him to pieces. Kronos then threw his remains into the sea as a gesture of disgrace to Oceanus, who had refused to help take down their father. From the spot where Ouranos' genatalia landed formed sea foam, from which Aphrodite emerged. Ouranos then cursed Kronos, stating that his child would come to overthrow him, just as he had. Nothing was mentioned about Ouranos afterwards, since his form was spread so thin that was never able to form a consciousness again.

The Lightning Thief
Poseidon mentioned Ouranos to his son Percy Jackson, while discussing his father Kronos.

The Titan's Curse
Ouranos does not formally appear but he is mentioned by the General. It is said that a Titan must hold up the Sky because Ouranos is gone and the Sky still longs to embrace the Earth. Atlas, a Titan, is assigned this torment as of the First Olympian War.

The Battle of the Labyrinth
Ouranos and Gaea are mentioned by Annabeth and a naiad.

The Lost Hero
Coach Hedge mentioned him when he was telling the story of Gaea and how she convinced Kronos to take a scythe and kill Ouranos. When he said that, Piper McLean looked at the sky, as if seeing if it had eyes and a mouth, possibly wondering of Ouranos, her grandfather.

The House of Hades
Ouranos was mentioned when Bob and Krios talked about holding him down while Kronos cut him into little pieces.

The Blood of Olympus
While searching for a way to defeat Gaea, Jason Grace asks Kymopoleia for advice and she reminds him of Ouranos' defeat, which proves that a primordial god can be defeated. Taking inspiration from the Titans' defeat of Ouranos, Leo Valdez comes up with a plan that Apollo confirms could work but would kill any mortal nearby. After the rise of Gaea, Leo, Festus, Jason and Piper McLean carry Gaea high into the sky. They cut her off from the source of her power as the Titans did to Ouranos. This was the weakness Kymopoleia earlier hinted at. Gaea's essence ends up scattered by Leo and Octavian and its later stated that like the sky after Ouranos' defeat, the Earth continues to exist without Gaea and continue on as normal.

Personality
As shown in Percy Jackson's Greek Gods, Ouranos was a self-absorbed, pompous, cruel being. He also had a ferocious temper, and due to his surpassing power, none of the other Protogenoi dared challenge him. Despite having feelings for Gaea, neither Pontos, nor Tartarus acted on their feelings due to Ouranos' marriage with her. In Percy Jackson's Greek Gods, it is stated that his son Kronos had inherited his infamous cruelty and bad temper from Ouranos.

Ouranos was a terrible father, and he did not care for his children at all. He ignored the Titans, and hurled the Elder Cyclopes and Hekatonkheires into Tartarus merely for how they looked. He was a terrible husband too, barely spending time with Gaea and taking cruel pleasure in throwing both sets of their triplets into Tartarus. However, it is possible that Ouranos loves or desires her somewhat, although it is unclear where he is or what he is doing, as stated in the The Titan's Curse by Atlas, who said, "The Sky still yearns to embrace the Earth."

Appearance
In Percy Jackson's Greek Gods, Ouranos is described as looking tall and muscular, with long dark hair. He only wore a loincloth, and his skin changed color - sometimes blue with cloudy patterns (during the day), sometimes dark with glimmering stars (during the night).

Abilities
The King of the Protogenoi and the embodiment of the Heavens, Ouranos was one of the most powerful entities in the series (perhaps second only to Chaos). Infinitely powerful in his domain, he was only defeated when lured down to earth. Even then, he was only defeated by the combined efforts of five of his sons and his wife, Gaea.
 * Massive Strength: Ouranos easily overpowered the Elder Cyclopes and the Hundred-Handed Ones, chaining them up and hurling them into Tartarus (albeit, they were newborns at the time). Furthermore, it took four of his Titan sons,who were among The Most Powerful and Strongest Titans to ever exist,to pin him down, and even then, he put up a fierce fight.
 * Creation of Sentient Life Forms: In Percy Jackson's Greek Gods, Ouranos' blood was shown to have so much power that many sentient life forms (possibly including the Furies), sprang from it over the millennia. His sliced and mangled remains also created Aphrodite, an Olympian Goddess.
 * Atmokinesis: As protogenos of the Sky, he has absolute control and divine authority over the weather.
 * Aerokinesis: As protogenos of the Sky, he has absolute control and divine authority over the air.
 * Chains of Darkness: As seen in Percy Jackson's Greek Gods, Ouranos could use the darkness of the night sky to generate extremely durable black chains, with which he bound his Elder Cyclopes and Hekatonkheire children before flinging them into Tartarus.
 * Supreme Power: Ouranos has immesurable levels of power far superior to that of any of the Olympians, Giants, and Titans, seeing as he is the first High God and was able to chain up and throw many of his powerful children into Tartarus single-handedly (a feat that required Kronos, Atlas, and Hyperion working together to later replicate). His power also exceeds that of any of the Protogenoi (save Chaos). As seen in Percy Jackson's Greek Gods, Gaea did not dare attack him without aid. Kronos feared for Ouranos' wrath on all the Titans and on Gaea if their assassination failed. It was also mentioned that before Kronos, nobody dared oppose him.
 * Tongue of the Old Times fluency: According to Tyson in The Battle of the Labyrinth, this is the ancient language that Gaea spoke to the Titans, Elder Cyclopes and Hekatonkheires before the birth of the Olympian gods. Ouranos and Gaea must have communicated in this language as well.

Trivia

 * Ouranos' first and only appearance was in Percy Jackson's Greek Gods.
 * The 7th planet from the sun, Uranus, is named after him.
 * In some myths, Ouranos was born as a son of Gaea before he became her consort.
 * It is mentioned that Gaea cannot be defeated and can only be kept asleep; however, it is unknown why Ouranos actually died when Kronos cut him to pieces. However, since Atlas said that "the sky still longs to embrace the earth", Ouranos may still be alive in some form.
 * Kronos, like Ouranos, was cut to pieces with the scythe but his essence continued existing, albeit imprisoned within Tartarus. This could mean that Ouranos himself is still alive in some form of consciousness, existing without a physical body.
 * It has also been speculated by some scholars of Greek mythology that after Kronos castrated him, he fled away back to his domain in fear of the scythe. It could be that Gaea had crafted the scythe specifically to harm Ouranos.
 * It's also possible that Ouranos faded when his youngest grandchild Zeus became Lord of the Sky.
 * Ouranos may have been scattered like Kronos and Gaea ultimately were. It was shown with the defeat of Gaea that even the primordial gods could be beaten in this way and mention was made of Gaea now being like Ouranos suggesting he too was scattered.
 * Ouranos is the father of Kronos, who is father of Zeus, Poseidon, and Hades, making Ouranos the great-grandfather of Percy Jackson, Thalia Grace, Jason Grace, Hazel Levesque, Bianca and Nico di Angelo.​
 * He's the grandfather of the Big Three.
 * The periodic element Uranium is named after him.
 * Aphrodite emerged from the sea foam which formed where the pieces of Ouranos' genatalia were thrown into the sea by Kronos, therefore technically making him her father and the grandfather of the members of the Aphrodite Cabin.
 * Ouranophobia (also known as Uranophobia) is the fear of heaven, which is named after Ouranos.
 * The Romans simply Latinized his name as "Uranus", with which they call him most of the time. However, they do have an non-Greek Latin name for Uranus, and it is "Caelus".
 * The French word Ciel which means "Sky" is derived from his Latin name, Caelus.
 * It is implied that since Kronos destroyed his mortal form, Ouranos is unable to return to earth.
 * The Seven got inspiration from Ouranos' defeat in order to defeat his wife Gaea.
 * His Egyptian equivalent is Nut.