Marian Hillar M.D., Ph.D., is an American philosopher, theologian, linguist, and physician. He is a recognized authority on Michael Servetus' influence in the world and the development and ideas of the Socinian movement in the 16th and 17th centuries. He does research in the history of ideas and is author of some works concerning Servetus, and some translations of Servetus's works.
Marian Hillar was born in 1938 in Bydgoszcz (present-day Poland) in an old family claiming its roots in 14th century Holland. He received classical education in highly selective elementary and secondary schools with emphasis on science and languages. He earned his degrees at the Medical University of Gdansk and studied at the Jagiellonian University and at Sorbonne. He was invited in 1969 to do research at Baylor College of Medicine in Houston. He became a US citizen in 1977. He did research and taught in Europe at the Medical University of Gdansk and the Università degli studi di Camerino, and in the USA at the Baylor College of Medicine and the Ponce School of Medicine. He is currently professor of philosophy and religious studies, and he is director of the Center for Philosophy and Socinian Studies which he founded in 1986.
 History of philosophy and religion
Marian Hillar has done studies of the philosophy of Hippocratic medicine; Greek philosophy of science and the origin of science; ancient Greek philosophy; liberation theology; studies on the New Testament, Dead Sea Scrolls, early Christian writers, and the origin of Christianity; Philo of Alexandria, Numenius, early church fathers and development of the theory of logos and of the Trinity; studies in ethics- Stoics, Thomas Aquinas, Kant; Radical Reformation and development of antitrinitrian doctrines, socinians; development of modern ideas on freedom of conscience and church-state separation.
Some scholars have noted errors on Hillar's works, such as assuring that the Bible Cum Glossis by Servetus (1545), was signed by Michael. This statement was proved to be false by servetian Gonzalez Echeverría, who found a copy of the anonymous Bible, originally referred by researcher Julien Baudrier. This shows this work was referred trusting the content of secondary sources, and not checked from the archival source.
Hillar is editor-in chief and founder of the Essays in the Philosophy of Humanism, a scholarly journal published yearly since 1992 by the Humanists of Houston. In 2005, the American Humanist Association, Washington, DC, agreed to assume the duties of publishing the journal under its aegis.
 Select publications
- Marian Hillar, "Energetics and Kinetic Mechanisms of Enzyme Function", pp. 685, Whittier Publications, Lido Beach, New York, 1994.
- Marian Hillar, "The Case of Michael Servetus (1511-1553) - The Turning Point in the Struggle for Freedom of Conscience," pp. 444, The Edwin Mellen Press, Lewiston N.Y., 1997; second printing in 1999.
- Marian Hillar with Claire S. Allen, “Michael Servetus: Intellectual Giant, Humanist, and Martyr,” pp. 274+xxvii. (Lanham, New York, Oxford: University Press of America, 2002).
- Marian Hillar, and Christopher A. Hoffman, translators: “The Restoration of Christianity. An English Translation of Christianismi restitutio, 1553, by Michael Servetus (1511-1553). Translated by Christopher A. Hoffman and Marian Hillar,” (Lewiston, NY; Queenston, Ont., Canada; Lampeter, Wales, UK: The Edwin Mellen Press, 2007).
- Marian Hillar, and Christopher A. Hoffman, translators: “Treatise on Faith and Justice of Christ’s Kingdom by Michael Servetus. Selected and Translated from Christianismi restitutio by Christopher A. Hoffman and Marian Hillar,” (Lewiston, NY; Queenston, Ont., Canada; Lampeter, Wales, UK: The Edwin Mellen Press, 2008).
- Marian Hillar, and Christopher A. Hoffman, translators: “Treatise Concerning the Supernatural Regeneration and the Kingdom of the Antichrist by Michael Servetus. Selected and Translated from Christianismi restitutio by Christopher A. Hoffman and Marian Hillar,” (Lewiston, NY; Queenston, Ont., Canada; Lampeter, Wales, UK: The Edwin Mellen Press, 2008).
- Marian Hillar, and Christopher A. Hoffman, translators: “Thirty Letters to Calvin & Sixty Signs of the Antichrist by Michael Servetus.” Translated from Christianismi restitutio by Christopher A. Hoffman and Marian Hillar (Lewiston, NY; Queenston, Ont., Canada; Lampeter, Wales, UK: The Edwin Mellen Press, 2010). Pp. 175 + lxxxvi.
- Juan Naya and Marian Hillar, eds., “Michael Servetus, Heartfelt: Proceedings of the International Servetus Congress, Barcelona, 20-21 October, 2006,” (Lanham, MD and Plymouth UK: University Press of America, 2011). 430 pp.
- Marian Hillar, "From Logos to Trinity: The Evolution of Religious Beliefs from Pythagoras to Tertullian," pp. 332, Cambridge University Press, 2012.
 See also
- "The Philosophical Legacy of the 16th and 17th Century Socinians: Their Rationality", The Proceedings of the Twentieth World Congress of Philosophy, at the XXth World Congress of Philosophy, 1998.
- Agnieszka Nietresta, "Malgorzata Hillar: Szkic Monograficzny", Wydawnictwo Homini, Krakow, 2003.
- Center for Philosophy and Socinian Studies
- González Echeverría, F.J. The Love for Truth. Life and works of Michael Servetus. Ed Navarro y Navarro. Zaragoza 2011. p 218-note 526
- Essays in the Philosophy of Humanism
- http://www.berkshirehumanists.org.uk/?p=1368 David McKnight, "Just in case you were beginning to think that Humanism was a simple concept..." December 1, 2008.
- http://www.servetus.org/ reproduces many papers of Hillar
- Book Review: "Michael Servetus: Intellectual Giant, Humanist, and Martyr"
- http://people.stfx.ca/wsweet/Book-Istanbul-TOC.htm "Numenius and Greek Sources of the Central Christian Theological Doctrine", The Proceedings of the XXI World Congress of Philosophy, Volume 8
- Marian Hillar's Website