Isaac ben Abraham of Dampierre

Isaac ben Abraham (יצחק בן אברהם), also called Rabbi Isaac ha-Baḥur (Hebrew: ר"י הבחור or רבי יצחק הבחור, which translates to "Rabbi Isaac the Younger") and by its Hebrew acronym RIBA (ריב"א) or RIẒBA (ריצב"א), was a tosafist of the late twelfth and early thirteenth centuries.

He succeeded his teacher Isaac ben Samuel as head of the school of Dampierre, after which place he is often called, as well as by the epithet Isaac ha-Baḥur ("the younger"), to distinguish him from his teacher, Isaac ben Samuel ha-Zaḳen ("the elder") (ר"י הזקן).