M. Rahim Shayegan (/ʃɑːjɛɡɑːn/, Persian: رحیم شایگان, romanized: M. Raḥīm Šāygān; born 1966) is an Iranian-born American ancient historian, scholar, and educator. He is the Eleanor and Jahangir Amuzegar Professor of Iranian Studies in the Department of Near Eastern Languages and Cultures at the University of California, Los Angeles. At UCLA, he also serves as the founding director of the Pourdavoud Institute for the Study of the Iranian World,^[1][2] the founding director of the Yarshater Center for the Study of Iranian Literary Traditions,^[3] and the Director of the Program of Iranian Studies (from 2014).^[4] He also is a foreign corresponding member of the Austrian Academy of Sciences (2022), a fellow of the Academia Europaea (2019) and the American Oriental Society^[5] and a Guggenheim fellow (2013, for writing the book Arsacids and Sasanians: Political Ideology in Post-Hellenistic and Late Antique Persia).^[4][5]

Son of Dariush Shayegan,^[4] Rahim Shayegan moved in the United States with his father after the Iranian revolution.^[6] He received his B.A. from the University of Cologne, Germany, and his M.A. from the University of Sorbonne (now University of Paris), France, followed by Ph.D. work at the University of Göttingen, Germany, and received his Ph.D. at Harvard University. He then became a Junior Fellow for the Harvard Society of Fellows (2000, thesis name Aspects of early Sasanian history and historiography).^[7]

Shayegan focused of his research in the Iranian philology and epigraphy, religion and the history of Iran, primarily the history of Achaemenid, Arsacid, Seleucid, and Sasanian periods.^[8]

Shayegan's most quoted and authoritative book Arsacids and Sasanians: Political Ideology in Post-Hellenistic and Late Antique Persia (2011) was to be translated into Persian, but the intended translator died shortly after starting the work. It is a study of the relations of the Iranian empires with Western states,^[4] political crises of the Parthian era and Sasanian rise to power,^[9] and speculation as to whether the Sassanids were aware of Iran's Parthian past.^[4] Arsacids and Sasanians: Political Ideology in Post-Hellenistic and Late Antique Persia received mixed reviews from professional Iranists. According to Sabine Müller [de] this book is a 'differentiated, thorough, lively, inspiring, and ambitious study'.^[10] According to Polish historian Marek Jan Olbrycht [pl] this is a provocative book and 'an engaging and vibrant piece of historical writing', but he noted that Shayegan appeared to have difficulty defining precisely the scope of his research, and this uncertainty was evident in the coherence and content of the book. At the end of the review, Olbrycht notes that on the one hand, Shayegan’s book is remarkable for its erudition and detail of its reasoning; but, on the other hand, it disappoints with its contradictions and shortcomings in methodology and partly in the way it analyzes sources. His fundamental hypotheses about the role of Babylonian scribes and Pontic ideology turn out to be untenable in the light of the available sources.^[11]

• Bakhos, Carol; Shayegan, M. Rahim, eds. (2010). The Talmud in Its Iranian Context. Tübingen: Mohr Siebeck. ISBN 978-3-161-50187-6.
• Shayegan, M. Rahim (2011). Arsacids and Sasanians: Political Ideology in Post-Hellenistic and Late Antique Persia (Illustrated ed.). New York: Cambridge University Press. ISBN 978-0-521-76641-8 – via Google Books.^[10]
• Shayegan, M. Rahim (2012). Aspects of History and Epic in Ancient Iran: From Gaumāta to Wahnām. Hellenic Studies. Vol. 52 (Illustrated ed.). Cambridge, MA: Center for Hellenic Studies, Trustees for Harvard University. ISBN 978-0-674-06588-8 – via the Center for Hellenic Studies . (translated into Persian)^[4]
• Shayegan, M. Rahim (2013). "Sasanian Political Ideology". In Potts, Daniel T. (ed.). The Oxford Handbook of Ancient Iran. Oxford and New York City: Oxford University Press. pp. 805–813. doi:10.1093/oxfordhb/9780199733309.001.0001. ISBN 978-0-19-973330-9 – via the Internet Archive.
• Shayegan, M. Rahim (2016). "Old Iranian Motifs in Vīs o Rāmīn". In Korangy, Alireza; Thackston, Wheeler M.; Mottahedeh, Roy P.; Granara, William (eds.). Essays in Islamic Philology, History, and Philosophy. Studies in the History and Culture of the Middle East. Vol. 31. Berlin: De Gruyter. pp. 29–51. doi:10.1515/9783110313789. ISBN 978-3-110-31372-7.
• Shayegan, M. Rahim (2017). "Persianism: Or Achaemenid Reminiscences in the Iranian and Iranicate World(s) of Antiquity". In Strootman, Rolf; Versluys, Miguel John (eds.). Persianism in Antiquity. Oriens et Occidens. Vol. 25. Stuttgart: Franz Steiner Verlag. pp. 401–457. ISBN 978-3-515-11382-3 – via Academia.edu.
• Shayegan, M. Rahim, ed. (2018). Cyrus the Great: Life and Lore. Ilex Foundation Series. Vol. 21 (First, Illustrated ed.). Boston: Ilex Foundation. ISBN 978-0-674-98738-8.^[12]
• Shayegan, M. Rahim (2022). "The End of the Parthian Arsacid Empire". In Gehler, Michael; Rollinger, Robert; Strobl, Philipp (eds.). The End of Empires. Universal- und kulturhistorische Studien / Studies in Universal and Cultural History. Wiesbaden: Springer Fachmedien. pp. 213–247. doi:10.1007/978-3-658-36876-0_9. ISBN 978-3-658-36876-0.

• Shayegan, M. Rahim (2003). "HAZĀRBED". In Yarshater, Ehsan (ed.). Encyclopædia Iranica. Vol. XII/1: Harem I–Hedāyat al-mota'allemin. London and New York: Routledge & Kegan Paul. pp. 93–95. ISBN 978-0-933273-74-0.
• Shayegan, M. Rahim (2004). "Hormozd I". In Yarshater, Ehsan (ed.). Encyclopædia Iranica. Vol. XII/5: Homosexuality III–Human migration II. London and New York: Routledge & Kegan Paul. pp. 462–464. ISBN 978-0-933273-79-5.