Cassandane or Cassandana (died 538 BC) was an Achaemenian queen and the wife of king Cyrus the Great, the mother of Cambyses II and Atossa and the grandmother of Xerxes I.

She had four children with 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.

[2] When Cassandane died, all the nations of Cyrus' Persian empire observed "a great mourning".

According to the Nabonidus Chronicle, there was a public mourning after her death in Babylonia lasting for six days.

Cassandane reportedly stated that it was more bitter to leave Cyrus's side than to die.