A converso, "convert", was a Jew who converted to Catholicism in Spain or Portugal, particularly during the 14th and 15th centuries, or one of their descendants.

New Christian was a socio-religious designation and legal distinction in the Spanish Empire and the Portuguese Empire. The term was used from the 15th century onwards primarily to describe the descendants of the Sephardic Jews and Moors baptised into the Catholic Church following the Alhambra Decree. The Alhambra Decree of 1492, also known as the Edict of Expulsion, was an anti-Jewish law made by the Catholic Monarchs upon the Reconquista of the Iberian Peninsula. It required Jews to convert to Catholic Christianity or be expelled from Spain. Most of the history of the "New Christians" refers to the Jewish converts, who were generally known as Conversos while the Muslim converts were known as Moriscos.