Deimachus or Daimachus (/diˈɪməkəs/; Ancient Greek: Δηΐμαχος or Δαΐμαχος) was a Greek from Plataeae, who lived during the third-century BCE. He became an ambassador to the court of the Mauryan ruler Bindusara "Amitragatha" (son of Chandragupta Maurya) in Pataliputra in India.Deimachus was sent by Antiochus I Soter.
As an ambassador, he was the successor to the famous ambassador and historian Megasthenes. Both of them were mentioned by Strabo.
