Mardavij (Gilaki/مرداویج, meaning "man assailant") was an Iranian prince, who established the Ziyarid dynasty, ruling from 930 to 935.
Born to a Zoroastrian family native to Gilan, Mardavij sought to establish a native Iranian Zoroastrian empire akin to the Sasanian Empire that had been conquered in the 7th century by the Rashidun Caliphate and subsequently ruled by Muslims. He first started his career by joining the army of his kinsman Asfar ibn Shiruya. Mardavij, however, later betrayed and killed him, conquering much of Jibal. He then set out to conquer Hamadan, Dinavar and Isfahan from the Abbasid Caliphate, and thereafter declared himself king of Iran, making Isfahan his capital.
He then defeated the Daylamite military leader Makan ibn Kaki, and conquered Tabaristan in 932. By 934, his authority was acknowledged as far as Shiraz and Ahvaz. However, his goal of recreating the Iranian Empire was ruined when he was murdered by his own Turkish slaves in 935.
Mardavij was born ca. 890 in Gilan; he was the son of Ziyar, who belonged to the Shahanshahvand, a royal clan that roamed around Dakhel. Mardavij's mother was a sister of Harusindan, a Gilaki ruler. Mardavij belonged to the Arghich tribe, which claimed to be descended from Arghush Farhadan, king of Gilan who lived during the time of Kay Khosrow. Mardavij grew up in an environment where memories of the glories of the Iranian Empire were alive in the Iranian culture. According to the 10th-century Arab historian al-Masudi, most of the Daylamite and Gilaki leaders, who were Zoroastrian and pagan, had become atheists. Mardavij was one of the many Gilaki leaders that entered into the service of the Alids, once they had established their rule over Tabaristan, Gilan, and Daylam.
Around 913, Mardavij joined the army of Asfar ibn Shiruya of Lahijan, who served the Zaydids of Tabaristan. In 930, Asfar invaded the domains of the Zaydi Abu Muhammad Hasan ibn Qasim. During the invasion, Mardavij managed to heavily wound Abu Muhammad near Amol, thus avenging his maternal uncle Harusindan, who was killed by the hands of the Alids.