Morpheus

Morpheus (Μορφέας in Ancient Greek ) is the god of dreams and the son of Hypnos and Pasithea. In some myths he is the son of Hades. Iris is his suspected wife. He is also known as "The Shaper". His symbols are a closed eye and a dark crown. Mortals call him the Sandman.

Appearance
Morpheus is described as a tall man in a long black coat. He does not cast a shadow (even at midday) and shimmered as he moved like a mirage. His face cannot be made out, as it shimmers and changes when looked upon.

The Battle of the Labyrinth
Morpheus is mentioned in The Battle of the Labyrinth as one of the minor gods who've gone over to Kronos' side.

The Last Olympian
When Percy and Nico woke Grover up to get his help to enter the Underworld, Grover told him what had happened. During June in the woods in Harlem Meer, Grover saw Morpheus. Morpheus, in his words, was scouting the battlefield before the battle, and put Grover to sleep (for two months). Later, Morpheus had cast a huge sleeping spell (suspected with the help of Hecate to spread the spell) which causes all of the mortals in Manhattan or near Manhattan to instantly fall asleep. This event was described in the line of the Great Prophecy: "And see the world in endless sleep."

Powers

 * Morpheus is the god of dreams, so he can make people fall asleep.
 * When looking at his face, it makes the viewer sleepy.
 * Whenever he passes humans, the human would pass out, curl up and fall asleep, and after he had gone, they would wake up and act as if nothing had happened.
 * He can send images to humans in dreams.
 * He can shape people's dreams.
 * Was able to put New York to sleep, but he could not do this to the heroes.
 * Morpheus has the ability take any human form and appear in dreams.

Trivia

 * It is not certain if he has any demigod children. In The Last Olympian, Percy asked for a cabin to be built for him, like the other minor gods, although it was never mentioned afterwards.
 * Like the other minor gods that had sided with Kronos, he was probably forgiven after the war.
 * Grover (who has the ability to feel when something was wrong in nature) was able to sense him as he made the ground tremble, like something powerful was near.
 * The word Insomnia (a sleeping disorder) was named after Morpheus's Roman name, Somnia.
 * Since the spell he put on Manhattan was unable to affect the demigods fighting against Kronos, it can be presumed that there are no other demigods living in Manhattan. (Unless the spell affected unclaimed demigods or the people who were awake stayed inside.)
 * The drug 'Morphine' is named after him.
 * While Morpheus is the god of dreams, his powers seem to overlap with Hypnos, god of sleep.