Abiathar Crescas (Aragonese: [aβiaˈtar ˈkɾeskas], Catalan: [əβiəˈtar ˈkɾeskəs]) was a 15th-century Jewish physician and astrologer from the Crown of Aragon (now part of Spain). He was head astrologer to King John of Aragon, father of King Ferdinand of Aragon.

Crescas was a very prominent Jewish figure in Aragon. He could remove cataracts by a surgical procedure known as couching, and was most famous for restoring the eyesight of King John in two simple operations.