In Greek mythology, Cychreus (Ancient Greek: υχρεύς) was a legendary king of Salamis Island. He was the son of the god Poseidon and the nymph Salamis. Various accounts describe Cychreus as a figure associated with serpentine symbolism: in some versions, he fought a dragon or serpent named Cychreides that was terrorizing the island; in others, he raised a serpent as a pet or was himself called "the dragon" for his fierce temperament.
Cychreus is linked to both the mythology of Salamis Island and early Athenian traditions, where he became part of Athens's cultural and political narrative. His legacy includes connections with the founding myths of Athens and later figures, including the heroes Telamon and Ajax the Great, who were associated with Salamis. Athenian leaders, such as Solon and Themistocles, referenced Cychreus to reinforce claims over Salamis, and a sanctuary dedicated to him was reportedly established there. His story reflects broader themes in Greek mythology, where local heroes were integrated into the identities and political aspirations of city-states.