Paulus Weidner von Billerburg (né Nathan Ashkenazi;^[1] 1525–1585) was a Jewish convert to Christianity, a medical doctor, and professor of Hebrew at the University of Vienna.

Nathan Ashkenazi was born into a Jewish faith (the businessman and medical doctor Solomon Ashkenazi was an elder brother) in Carinthia.^[1][2] He studied medicine at the University of Padua,^[1] and practiced at Udine,^[2] from whence he was called back to his homeland by the Estates of Carinthia to practice medicine there.^[1][2]

During a six-year stay in Carinthia, after careful study of his and the Christian religion, he decided to become a Christian.^[2] Realising the danger that threatened him on the part of his co-religionists, he kept his intention secret for a year, and having made up his mind, he left Carinthia and went to Vienna.^[2]

Weidner joined the Roman Catholic Church in Vienna in 1558.^[1][2] He received thereafter the patronage of successive Austrian emperors, who employed him as personal physician and even consulted him on certain matters.^[1] On 13 March 1560, Emperor Ferdinand I confiscated all the Hebrew books of the Bohemian Jewry, and had them brought to Weidner in Vienna for scrutiny; he found no fault in them, and had them sent back to Prague.^[1]

Weidner was professor of Hebrew at the Vienna University, and was appointed by Imperial permission to preach occasionally to the Jews.^[3] He was six times dean of the faculty of medicine and thrice rector of the university.^[1] He was ennobled, with the title "von Billerburg", in 1582.^[1] He died in Vienna in 1585.^[2]

His first work, Loca Praecipua Fidei Christianae Collecta et Explicata (Vienna, 1559; 2nd edition 1562, with Epistola Hebr. ad R. Jehudam, Venet. Habitantem, cum Vessione Latina), is particularly aimed at the Jews, to convince them of the truth of Christianity.^[2][1] He dedicated this work, in the preface to which he gives information about his life and conversion, to Emperor Ferdinand.^[2] Weidner's last published work was Sententiae Hebraicae (1563), a collection of proverbs.^[1]

• History of Jewish conversion to Christianity
• List of converts to Christianity from Judaism

• Pick, B. (1881). "Weidner, Paul". In McClintock, John; Strong, James (eds.). Cyclopædia of Biblical, Theological and Ecclesiastical Literature. Vol. 10.—Su–Z. New York: Harper & Brothers. p. 899. This article incorporates text from this source, which is in the public domain.
• Skolnik, Fred; Berenbaum, Michael, eds. (2007). "Weidner, Paulus". In Encyclopaedia Judaica. 2nd ed. Vol. 20.—To–Wei. The Gale Group. p. 699. ISBN 978-0-02-865948-0.
• Wurzbach, Constantin von (1886). "Weidner, Paul". In Biographisches Lexikon des Kaiserthums Oesterreich. Vol. 53. Vienna: K.K. Hof- und Staatsdruckerei. p. 275.