Thaʽlab (ثعلب), whose kunya was Abū al-ʽAbbās Aḥmad ibn Yaḥyā (ابو العباس احمد بن يحيى) (815 – 904) was a renowned authority on grammar, a muhaddith (traditionist), a reciter of poetry, and first scholar of the school of al-Kūfah, and later at Baghdād. He was a keen rival of Al-Mubarrad, the head of the school of al-Baṣrah. Thaʽlab supplied much biographic detail about his contemporary philologists found in the biographical dictionaries produced by later biographers.