Cephalus was a figure in Greek mythology, son of the ruler of Phocis, Deion, and Diomede. He was married to Procris, daughter of the king of Athens Erectheus and Praxithea. However, he was kidnapped by the goddess of dawn, Eos, and they became lovers. Cephalus never stopped loving Procris, though, which caused the discontent of Eos and eventually, she returned him to his wife.
Eight years had passed when Eos let Cephalus go back to his wife; so, he decided to return in disguise and seduced Procris. She was ashamed, and went to hunt with Artemis in the forest. After returning, she brought back two gifts, a javelin that never missed, and Laelaps, a hunting dog that always caught its prey.
Procris was happy that her husband returned to her, but she wondered how faithful he was to her. So, when he went to a mountaintop to invoke Nephele, she followed him. Cephalus heard a noise and not knowing it was his wife following, he threw the javelin thinking it was an animal. Procris was mortally wounded and just before she died, she asked Cephalus never to marry Eos.
Cephalus, distraught, exiled himself. After wandering for a long time, he ended up in an island where he eventually married his second wife and became the ruler of the area. The island was named after him as Cephallenia or Cephalonia. However, he never managed to recover from the death of Procris and committed suicide by falling from a cliff into the sea.