Perseus

Perseus was a son of Zeus and Danae, and one of the only heroes in Greek mythology to have a happy ending. He was mentioned in the Percy Jackson and the Olympians series many times.

History
His mother, Danae, was locked in a prison by her own father, King Acrisius of Argos. The King had heard a prophecy that told that his daughter's son would one day kill him. Instead of taking the risk that his daughter would become pregnant, he locked her away in a tower with no doors, and only one small window. Zeus saw the lovely princess, fell in love with her, turned himself into a shower of gold, and slipped through the window. He turned the prison into a lovely meadow filled with sun. Danae's father saw light coming from the window and demanded that a wall be torn down so he could check on his daughter.

When the wall came down Danae could be seen holding a baby boy. Afraid by angering Zeus, King Acrisius put the mother and child in a chest and shoved into the ocean letting the sea do the killing instead, but Zeus protected them along the way. They washed up on the shore of an island and were greeted by Dictys (a fisherman). Perseus grew up quite happily until one day King Polydectes decided he wanted to marry his mother.

Danae was not interested in marrying Polydectes however. Unfortunately, the king wasn't taking no for an answer, but Polydectes couldn't get around Perseus, so instead he pretended to marry someone else. When Perseus came to the wedding without a gift (he couldn't afford one) the King demanded that Perseus bring him Medusa's head as a gift.

Perseus went on a long quest, ended up slaying Medusa (the Gorgon), with the assistance of Hermes, god of travelers (who loaned him his sword, which was previously used to slay Argus, and winged sandals), Athena, goddess of wisdom (who gave Perseus a mirror shield), and Hades the ruler of the Underworld (who gave Perseus the Helm of Darkness to hide in the shadows). He also, at one point, took away the Gray Sisters' eye to taunt them into telling him of the position of the Island of the Gorgons. However, on his way back to the king, Perseus showed the true nature of his heroism: Saving Princess Andromeda from the sea monster, Keto, who he later married.

Eventually, he takes the head back to King Polydectes only to find out the wedding was a sham and that his mother has been forced to be the King's wife. Furious, Perseus uses Medusa's head to turn his enemies in the Kingdom to stone, thereby rescuing his mother. Eventually, later in his life, he was playing in the Olympics when a gust of wind threw his discus at his grandfather, killing the old man (despite his best efforts).

Perseus then lived a long and happy life with his mother, children, and wife Andromeda, where he eventually died and achieved Elysium. Much much later Perseus and Andromeda are placed into the sky as constellations.

Trivia

 * Perseus is the demigod son of Zeus, opposed to Percy Jackson who is the demigod son of Poseidon.
 * Perseus is the half-brother of the hero, Heracles and his great-grandfather.
 * He is possibly a cousin to Percy because Percy is the nephew of Zeus and Zeus is the father of Perseus.
 * The constellation Perseus is named after him.
 * Percy has a lot in common with Perseus.
 * Sally Jackson named her son, Percy, after him because he was one of the only heroes in the myths to have a happy ending.
 * Percy beheads Medusa like his namesake Perseus.
 * In the original myth, Perseus threatened the Gray Sisters by taking away their eye in exchange for information. Percy did the same in The Sea of Monsters.