Kawus / Caoses Sasanian prince and governor of Tabaristan

Kawus (or Kayus; early Islamic sources: کیوس) was the eldest son of Kavadh I, the Sasanian emperor of Iran. During the late reign of his father, Kawus was appointed as governor of Tabaristan, and was given the title of Padishkhwargar Shah (king of Padishkhwargar).

Kawus was probably named after the mythical/legendary king Kay Kawus (Avestan: Kauui Usan). The names of his father and his brothers also suggest a renewed late Sasanian interest in the Iranian legendary history and particularly the Kayanid Dynasty.

Kawus might have initially been the heir presumptive to the Sasanian throne. However, following the outbreak of the Mazdakite revolt, Kawus was accused of supporting Mazdak and adhering to his heresy. His younger brother, Khosrau I who was known for his support of orthodox Zoroastrianism, was favoured by the nobles and the Zoroastrian clerics. As a result, Kawus was passed over as the heir and the throne was offered to Khosrau.

During the late reign of his father, Kawus was appointed as governor of Tabaristan in circa 520, and was given the title of Padishkhwargar Shah (king of Padishkhwargar).

In 530 or 537, Kawus aided Khosrau I in defeating the Turks, and conquered Ghazni. However, when Kawus returned to Tabaristan after his victory, he rebelled, and claimed the Sasanian throne from Khosrau. He was, however, defeated and brought to Ctesiphon, where he was given the option to confess his sins or die. Kawus chose death