According to mythology Kefalonia, was named after hero Kefalos, the son of Hermes and Ersi. Kefalos was married to Prokrida, the daughter of Erehthion.
There are many different myths associated with Kefalonia, myths without any logical unity or chronological equilibrium. According to Apollodorus of Athens, the island’s first king was Taphius, son of Poseidon and Hippothoe,daughter of Mnestor, king of the Myceneans.
Taphius’s son was Pterelaus, whose grandfather Poseidon gave him a golden hair which made him immortal as long is it stayed on his head. When the city of Kefalonia, which had by that time become quite powerful, demanded a substantial part of the kingdom held up to them by the Myceneans (the descendants of the legendary king Perseus), their king Electryon refused. In retaliation, the Taphians stole his flocks. Electryon never forgave them, and when Amphitryon, king of Thebes, asked for his daughter Alcmene’s hand in marriage, Electryon agreed, on the condition that Amphitryon take revenge for him. Amphitryon, aided by Kefalos and Eleius, set out to conquer Taphus. They never would have defeated the immortal king, had it not been for Comaetho, the daughter of Pterelaus, who fell in love with Amphitryon. One night, as her father lay sleeping, she cut the magic hair off his head. Pterelaus, now mortal, was defeated, his treacherous daughter put to death, and Amphitryon returned to Thebes after handing over the spoils to his fellow-warrior, Kefalos
Just who was that mythical hero Kefalos, who gave the island his name? Apollodorus informs us that Kefalos was the son of Hermes and Herse, the daughter of Cecrops, and that he belonged to the race of Cephalidae from Thoricus in Attica. (There are, however, suspicions that the myth was invented for political purposes by the Athenians in the 5th century BC). Another myth has it that Kefalos was the son of the king of Phokis, Deloneus, and yet another presents him as the son of Pandion and Creusa.
A number of myths have been invented about the erotic and marital adventures of Kefalos, a handsome man and intrepid hunter. He married Procris, daughter of the king of Attica Erechtheus and Praxithea. Kefalos was very much in love with her. Ovid tells the following story:
It was during the second month of their marriage, and Kefalos “was spreading his nets on the peak of Mt. Hymettus to catch deer with big antlers, when Eos (the Dawn) appeared before him in a chariot with the intention of kidnapping him. In vain did the poor mortal struggle against the goddess, pleading his recent marriage and his love for his legal wife. Finally the goddess, seeing him so unwilling, freed him, but not until she had sown a few doubts about his wife’s fidelity. In disguise, the suspicious husband returned to his wife and offered her his treasures. When her categorical refusal slowly began to falter, Kefalos, furious, revealed his true identity. The shamed wife went off to live in the mountains of Crete, where she became a huntress. Artemis, seeing that she was repentant, gave her a hunting dog, Laelaps, who always caught his quarry, and a spear that always found its mark. Then she turned Procris into a man and sent her home to her husband. She invited Kefalos to take part in a hunting contest and when she was victorious she revealed her true identity. The “deceived” husband realised his mistake and they lived happily together for many years.