Hypnos is the god and personification of sleep in Greek mythology, son of Nyx (and Erebus in some depictions) and the younger twin brother of Thanatos and older brother of Moros, Charon and many others. He is said to be a calm and gentle deity, as he helps humans in need and, due to their sleep, owns half of their lives. Hypnos is often depicted as a young man wrapped in poppy stock, a horn in his hand, and sometimes wings on his head.
He lives in a cave with the entrance dotted by narcotic flowers which appears in the Greek underworld, specifically Erebos, a wall that surrounds it. According to some stories, Hypnos lives instead in a big cave, which the river Lethe comes from and where night and day meet. His bed is made of ebony, on the entrance of the cave grow a number of poppies and other hypnotic plants. No light and no sound would ever enter his grotto.
According to Homer, he lives on the island Lemnos, which later on has been claimed to be his very own dream-island. His children had sometimes been claimed as the Oneiroi (Morpheus, Phobetor and Phantasos), the gods of dreams along with his wife being Pasithea. In some other depictions, the Oneiroi are the younger children of Nyx and Erebus which makes them Hypnos' younger siblings.
Hypnos is found in a dead end in the Second Sphere of the Womb of Grief. The protagonist can only access this part of the map after they have attained Gate Search B from Zelenin during Sector Delphinus. He introduces himself as a servant of Zeus, and as a token of gratitude for freeing him, he becomes available for fusion.
Shin Megami Tensei: Devil Summoner[]
"Origin: Greece
The god of sleep, and the son of the goddess of night, Nyx. He appears as a beautiful young man.
Hypnos dwells in the Underworld where light never reaches, sleeping on a soft bed surrounded by dreams.
He is a benevolent and kind person, bestowing dream to those who are tired. His abilities are so powerful that not even the mighty Zeus could resist."
—Akuma Zesho
Megami Ibunroku Persona[]
Hypnos appears as the boss of the Hypnos Tower in the Snow Queen Quest. The Snow Queen granted Hypnos as a guardian to Kumi Hirose, which she used to put the school faculty and students to sleep so they could live their dreams forever.
Megami Ibunroku Persona Manga[]
Hypnos appears in the 33th and 34th chapters of the manga, with a role identical to his game counterpart. He was defeated by Maki Sonomura at the start of the 34th chapter with Tensen Nyannyan's Heat Wave spell.
Persona 3[]
Hypnos is Takaya Sakaki's artificially summoned Persona, born from the experiments performed by the Kirijo Group. Surprisingly enough, Takaya is able to summon Hypnos without the aid of an Evoker. Hypnos appears as a disfigured body held in the air by wings seemingly grafted into his spine.
Level, HP and stats are dependant on the order in which the towers are conquered and whether or not the protagonist pinched Kumi Hirose in the Dream World.
It is possible to hack Hypnos for the Persona 3protagonist to use, but unlike party member Personas, he has no voice clip for Hypnos, instead a different Persona's clip, i.e. "Rangda!" will play instead. As the Persona has no default stats, level or other data (all of which come from Takaya's enemy data himself), even Arcana, without any further codes to change their stats and abilities, the game will crash when using it. There is a picture of Hypnos among the rest of the Personas.