Who is the Greek god of dreams and son of Hypnos?

The Greek god associated with dreams and identified as the son of Hypnos is Morpheus.

Morpheus is best known as a dream-shaping deity who appears in human form during sleep. His name comes from the Greek word morphē, meaning “form” or “shape,” reflecting his ability to imitate a person’s appearance, voice, clothing and mannerisms. He is especially associated with dreams involving human beings.

The fullest surviving ancient account comes from Ovid’s Metamorphoses, where Morpheus is described as one of the thousand sons of Somnus, the Roman equivalent of the Greek Hypnos. Ovid tells how the goddess Iris summons him to appear to the sleeping Alcyone in the likeness of her drowned husband, Ceyx, so she will learn of his fate.

Morpheus is commonly confused with Hypnos himself, who personifies sleep, and with Phobetor and Phantasos, his dream-related brothers. Phobetor takes the forms of animals, while Phantasos appears as inanimate things. The modern expression “in the arms of Morpheus” comes from his enduring association with sleep and dreams.