Converts to Roman Catholicism from Judaism

Ludwik Hirszfeld (Polish pronunciation: [ˈlud.vik xirʂfeld]; 5 August 1884 – 7 March 1954) was a Polish microbiologist and serologist. He is considered a co-discoverer of the inheritance of ABO blood types.

Julia Bertha Culp (6 October 1880 – 13 October 1970), the "Dutch nightingale", was an internationally celebrated mezzo-soprano in the years 1901–1919.

"You might describe Julia Culp as a connoisseur’s singer," Michael Oliver wrote in the International Opera Collector in 2000. "Her voice was not large, her compass not wide. She never sang in opera; striking dramatic gesture were not her line. What she excelled in were the singer’s rather than the vocal actress’s virtues: sustained legato line, remarkable breath control, subtle colour, immaculate care for words…. But ‘connoisseur’s singer’ does not mean that only connoisseurs can appreciate her; one becomes a connoisseur by listening to her."

Jean-Baptiste Gourion, O.S.B. Oliv. (24 October 1934 – 23 June 2005) was a French Catholic Benedictine monk who served as an Auxiliary Bishop of the Latin Patriarchate of Jerusalem from 2003 until his death in 2005.

Marc-André Raffalovich (11 September 1864 – 14 February 1934) was a French poet and writer on homosexuality, best known today for his patronage of the arts and for his lifelong relationship with the English poet John Gray.

Maxime Jacob, or Dom Clément Jacob, (13 January 1906 in Bordeaux – 26 February 1977 in En-Calcat Abbey, Dourgne, Tarn) was a French composer and organist.

Marcel Dassault (born Marcel Ferdinand Bloch; 23 January 1892 – 17 April 1986) was a French engineer and industrialist who spent his career in aircraft manufacturing.