In Greek mythology, Tereus (Ancient Greek: Τηρεύς) was a Thracian king, the son of Ares and husband of Procne. Procne and Tereus had a son, Itys.
Tereus desired his wife's sister, Philomela. He forced himself upon her, then cut her tongue out and held her captive so she could never tell anyone. He told his wife that her sister had died. Philomela wove letters in a tapestry depicting Tereus's crime and sent it secretly to Procne. In revenge, Procne killed her and Tereus' son Itys and served his flesh in a meal to his father Tereus. When Tereus learned what she had done, he tried to kill the sisters but all three were changed by the Olympian Gods into birds: Tereus became a hoopoe; Philomela became the nightingale whose song is a song of mourning for the loss of innocence; Procne became the swallow.
The names "Procne" and "Philomela" are sometimes used in literature to refer to the nightingale, though only the latter is mythologically correct.
Tereus was also a common given name among Thracians.
The Attic playwrights Sophocles and Philocles both wrote plays entitled Tereus on the subject of the story of Tereus.
Shakespeare refers to Tereus in Titus Andronicus, after Chiron and Demetrius have raped Lavinia and cut out her tongue and also both her hands.
Read more about Tereus: Modern Adaptations