In Greek mythology, Chthonic deities refer to gods and goddesses associated with the underworld, such as Hades and Persephone. They govern realms related to death, the afterlife, and the earth's fertility, bridging life and death. Often worshipped in ancient rituals, Chthonic deities underscore the belief in the cyclical nature of existence and the essential relationship between the living and the dead, emphasizing life’s transience.