New Christian is a law-effective and social category developed from the fifteenth century onwards, and used in what is today Spain and Portugal as well as their New World colonies, to refer to Sephardic Jews and Muslim Moors who had converted to Roman Catholicism, often by force or coercion.

It is developed and employed after the successful reconquest of the Iberian Peninsula by the Catholic Monarchs.By law, the category of New Christian includes not only recent converts, but also all their known baptized descendants with any fraction or quantum of New Christian blood up to the fourth generation, then in Phillip II's reign it includes any person with any fraction of New Christian blood "from time immemorial".

In Portugal, it is only in 1772 that the Marquis of Pombal finally decrees an end to the legal distinction between New Christians and Old Christians.