Thanatos is the Greek personification of death, often depicted as a young man with wings. He is the son of Nyx, the goddess of night, and is sometimes referred to as the twin brother of Hypnos, the god of sleep. In Greek mythology, Thanatos was responsible for ushering souls into the afterlife. He was also known for his role in the myth of Sisyphus, where he was sent by Zeus to take Sisyphus to the underworld.