David ben Yom Tov, also David Bonjorn del Barri, was a Catalan Jewish astronomer and astrologer who lived in the first half of the fourteenth century. He is reported to have been born at Cotlliure in Catalonia in around 1300, and to have died in Barcelona, probably before 1361.
In the past some scholars, including the nineteenth century scholar Moritz Steinschneider, have identified ben Yom Tov with the Portuguese Jewish scholar David ben Yom Tov ibn Bilia; this is now considered unlikely.
Sobrequés estimates that David ben Yom Tov was born at Cotlliure in about 1300. He was also called David Bonjorn, Bonjorn being a literal Catalan translation of the Hebrew Yom Tov, i.e. "good day".
His father was Bonjorn del Barri, a wealthy merchant of the province of Roussillon just north of the Pyrenees, which at that time was part of the Catalan Kingdom of Majorca. In 1323 del Barri is recorded as having been granted permission by King Sancho of Majorca to join the council of the Jewish community of Perpignan; and to travel and trade freely throughout the country, without having to wear a yellow badge or any other symbol to mark him out as a Jew. However by 1327 del Barri was dead, and David Bonjorn appears successfully petitioning James II of Aragon to relax various provisions of his father's will, including requirements on him to move from Cotlliure and reside in Perpignan for two years; to lend no money to the new king of Majorca or his courtiers until the king's twentieth birthday; nor to provide guarantees for anyone, apart from his own sisters; nor to take a lease on any royal incomes. Bonjorn appears to have been the only male heir; but his sisters mentioned in the document include one called Venges, who went on to become the wife of the celebrated Jewish author Joseph Caspi.