Pan

"The spirit of the wild must pass to all of you now. You must tell each one you meet: if you would find Pan, take up Pan's spirit. Remake the wild, a little at a time, each in your own corner of the world. You cannot wait for anyone else, even a god, to do that for you."

- Pan to Grover Underwood

Pan was the god of the Wild, hunting (partially), rustic music and folk music. Usually known as the son of Dryope and Hermes, although in some cases Pan predates Hermes and was perhaps raised alongside Zeus himself. Pan appears as an old satyr with incredibly large horns. His Roman counterpart is Faunus (when it came to forests, plains, and fields) and Inuus (when it came to cattle). In Roman myths, he is also a god of prophecy. Sometimes he's used to represent paganism (mainly in poetry).

History
Pan is the lost god of the Wild. Two-thousand years before the series, an announcement was made that the great god Pan had died which was accepted by most, except for the satyrs and nature spirits. Pan, while in Ephesos, told the satyr, Lysas to spread the word of his death. Like Satyrs, he was described as very lecherous, though this fact is absent in the series. Most satyrs dream of finding Pan and apply for a searcher's license through the Council of Cloven Elders so they can go looking for Pan. No satyrs ever return from the quest, because of the Golden Fleece which attracts them instead by giving out similar nature smell and feel (see Polyphemus). Grover Underwood had lost his father, grandfather, uncle, and probably more relatives and friends to the quest, but also figured out the Golden Fleece dilemma.

Pan once had a musical contest with Apollo. King Midas, one of Pan's followers, judged that Pan was the winner, despite Apollo being the god of music. In anger, Apollo gave Midas the ears of a donkey.

Pan also helped Zeus in the fight against Typhon (in the first war against Typhon). While Zeus was imprisoned by Typhon and held in a cave guarded by the female dragon Delphine, Pan started shouting out loud and caused panic in the dragon that ran away giving the god of lightning the chance to escape and to go after the son of Gaea.

Poetry
Pan appears a lot of times in poems normally representing the whole paganism or nature. The most famous one is this from Elizabeth Browning of which are part this two strophes:

And that dismal cry rose slowly

And sank slowly through the air,

Full of spirit's melancholy

And eternity's despair!

And they heard the words it said --

Pan is dead! Great Pan is dead!

Earth outgrows the myth fancies

Sung beside her in her youth,

And those debonair romances

Sound but dull before the truth,

Phoebe's chariot-course is run

Look up, poets, to the sun!

Pan, Pan is dead.

There were a poetic movement favorable to paganism so Elizabeth Browning wrote this poem to "remember" the poets of Greek Mythology were gone for good.

The Lightning Thief
Pan is mentioned as Grover needs to help Percy Jackson on his quest or he will not be able to get a searcher's license to find Pan. After successfully completing the quest, Grover leaves to search for Pan.

The Sea of Monsters
Grover's quest for Pan is not going well because of the Golden Fleece. The fleece gives off the same scent as the wild so it attracts satyrs to the island of Polyphemus where they are eaten. After bringing the fleece back to Camp Half-Blood, Grover sets out on the quest again in hope of finding Pan.

The Titan's Curse
While passing through New Mexico, Grover senses a strong presence and passes out saying something about the blessing of the wild. At the same time a Erymanthian boar flies out of the bushes attacking the groups enemies and later giving the group a ride west. Percy asks what Grover means and he says that he felt the presence of Pan. Grover thinks that Pan speaks to him through coffee when later on, Grover tells Percy that he heard Pan's voice say "I await you."

The Battle of the Labyrinth
During the quest in, Grover and Tyson split away from the group because Grover senses Pan. Later Percy, Annabeth Chase, Rachel Elizabeth Dare, and Nico di Angelo find them at a riverbank in the labyrinth. The group follows the river to a cave in the Carlsbad Caverns in New Mexico, where they find Pan lying on a bed. He fades in and out as he dies. He is surrounded by extinct animals that fade into dust as he dies. Pan tells Grover that he should have died two thousand years ago, but the satyrs prevented his passing. He says that it's his time to go and for Grover to carry on his wisdom to the world. He individually addresses Percy, Annabeth, Tyson, and Rachel, but does not address Nico. As Pan fades, some of his energy goes into everyone in the room with a little more going to Grover.

Then the group gets back to camp and are forced to battle Kronos' army. During the battle Grover releases a fierce scream which causes Kronos' army to flee in terror. Apparently the scream was an ability of Pan rightly named Panic. When Grover goes before the council the satyrs do not believe him, but Dionysus and Chiron do. The satyrs vote to exile Grover, but Chiron and Dionysus (whose vote counts for two since he is a god, and is upset so they do not challenge it) vote to keep him. Since the council reaches an indecision, it is disbanded, allowing Grover to remain. This unintentionally led to the slaughter of nearly twenty satyrs, the ones that had voted to exile Grover including Silenus and Maron. Leneus was spared, but his death was inevitable, and he died a hero in the Second Olympian War and was reincarnated into a laurel.

The Last Olympian
Pan's spirit is carried on in Grover who is joining the satyrs together to protect the wild places that are left in the world. He becomes "replaced" as Lord of the Wild by Grover.

The Mark of Athena
Once being freed from the Nymphaeum, and rejuvenated by Jason Grace, Percy, and Piper McLean, Hagno plans on exploring the world and visiting Pan. She comments that Pan wouldn't allow nature to become tainted, but Percy doesn't have the heart to tell her that Pan had faded before she leaves.

Faunus
Faunus is the Roman form of Pan. When Pan turns into Faunus, he becomes more disciplined, militaristic, and warlike. It is unknown if Faunus still exists as Pan faded away giving his abilities to Grover.

One of his sons was Tarquitus, who was killed by Aeneas.

Appearance
In The Battle of the Labyrinth, Pan is described as an old Satyr, with brilliant sky-blue eyes. His curly hair is white, as well as his pointy beard. Even the goat fur on his legs is frosted with gray. He has enormous curved glossy brown horns, and a set of reed pipes around his neck. Pan's laughter is described as sounding wonderful, like the "first breeze of springtime, filling the whole cavern with hope."

Abilities
Pan had the standard powers of a minor god, such as superhuman strength, immortality, control of the weather, etc.
 * Panic cry: this is Pan's signature and most powerful ability. According to Percy, the panic cry as the most horrible sound that he's ever heard, like a "brass trumpet magnified a thousand times—the sound of pure fear." In The Battle of the Labyrinth, the panic cry scares most of the Kronos' army invading Camp Half-Blood.
 * Pan presumably has woodland magic.
 * Pan has the powers of Grover and the other satyrs that they used throughout the series, but on a larger scale.
 * As shown in The Titan's Curse, Pan is able to make artificial images of animals come alive, often accompanied by a wave of nausea by satyrs, or a breeze of springtime by humans.
 * Pan can command the Erymanthian Boar and other creatures of the wild, such as a dodo bird, a mammoth and a tiger-wolf (quite possibly a Thylacine/Tasmanian Tiger) as seen in The Battle of the Labyrinth. It would also appear his power was the only thing keeping them alive, for once he faded, they turned to dust.
 * Pan can control things belonging to nature (water, rocks, dirt, animals, trees, and bushes).

Trivia

 * So far, Pan is the only being in the series that has actually been shown fading.
 * He is one of five immortals who are mentioned to have faded, the others being Helios, Selene, Cottus, and Gyges.
 * Pan is the first god that Rachel has met.