Cassandane or Cassandana (Ancient Greek: Κασσανδάνη Kassandanē) was an Achaemenian Persian noblewoman and the "dearly loved" wife of Cyrus the Great. She was a daughter of Pharnaspes. She bore four children for Cyrus: Cambyses II who succeeded his father and conquered Egypt, Smerdis (Bardiya) who also reigned as the king of Persia for a short time, a daughter named Atossa who later wed Darius the Great, and another daughter named Roxana.
Her daughter Atossa later played an important role in the Achaemenid royal family, as she married Darius the Great and bore him the next Achaemenian king, Xerxes I. Atossa had a "great authority" in the Achaemenian royal house and her marriage with Darius I is likely due to her power, influence and the fact that she was a direct descendent of Cyrus. When Cassandane died, all the nations of Cyrus' Persian empire observed "a great mourning". This is reported by Herodotus. According to a report in the chronicle of Nabonidus, there was a public mourning after her death in Babylonia lasting for six days. According to a suggestion by M. Boyce, Cassandane's tomb is located at Pasargadae.