Kartir (also spelled Karder, Karter and Kerdir; Middle Persian: 𐭪𐭫𐭲𐭩𐭫 Kardīr) was a powerful and influential Zoroastrian priest during the reigns of four Sasanian kings in the 3rd century.

[2] Shapur I religious practices seems to have been somewhat unusual, with animal sacrifice being made for the soul of the kings and queens of the Sasanian family.

[1] Shapur I died in 270, and was succeeded by Hormizd I, who gave Kartir clothes that were worn by the upper class, the cap and belt (kulāf ud kamarband) and appointed him as the chief priest (mowbed).

[5] Bahram I then made a settlement with his brother Narseh to give up his entitlement to the throne in return for the governorship of the important frontier province of Armenia, which was constantly the subject of war between the Roman and Sasanian Empires.

However, with Bahram I's accession to the throne, and the rise of the authority of the Zoroastrian priesthood and the increasing influence of Kartir, this changed; when Mani reached the city of Gundeshapur, much uproar occurred, in the same fashion as Jesus entry into Jerusalem.

The clergy from now on served as judges all over the country, with court cases most likely being based on Zoroastrian jurisprudence except when representatives of other religions had conflicts with each other.

[7] Under Bahram II, Kartir unquestionably becomes a powerful figure in the empire; the latter claimed on his inscription at the Ka'ba-ye Zartosht that he "struck down" the non-Zoroastrian minorities, such as Christians, Jews, Mandaeans, Manichaeans, and Buddhists.

[1] According to the modern historian Parvaneh Pourshariati: "[I]t is not clear, however, to what extent Kartir's declarations reflect the actual implementation, or for that matter, success, of the measures he is supposed to have promoted.

[6] The reasons behind the nobles' favour of Narseh might have been due to his jurisdiction as governor, his image as an advocate of the Zoroastrian religion and as an insurer for harmony and prosperity of the empire.

[6] Kartir fades into obscurity in historical records under Narseh, due to not doing anything noteworthy as mowbed "high priest".