Mihrak was a Parthian dynast, who was the ruler of Abarsas and Jahrom in the early 3rd-century. He was the son of Anoshagzatan, and belonged to a family which traced their descent back to the Kayanids. He was defeated and killed in ca. 222 during a clash with the first Sasanian king Ardashir I (r. 224-242). Mihrak had a daughter named Gurdzad (probably Khwarranzem), who later married Ardashir's son Shapur and bore him Hormizd.
Sources
Al-Tabari, Abu Ja'far Muhammad ibn Jarir (1985–2007). Ehsan Yar-Shater (ed.). The History of Al-Ṭabarī. Vol. 40 vols. Albany, NY: State University of New York Press.