"This catalogue is an indispensable tool for scholars of medieval philosophy and intellectual history alike." -- Reka Forrai, Central European University, Budapest, The Medieval Review This is the first of a projected series of four volumes describing manuscripts and fragments in British libraries containing commentaries on the Latin Aristotle. This volume covers the Bodleian Library and the college libraries of the University of Oxford. It lists 397 items, including portfolios of fragments from more than one original book, dating from the late twelfth century until c. 1500. While many of these manuscripts have come to Oxford from elsewhere in Europe, some as recently as the twentieth century, the majority were made locally and used in the medieval University. Many of them, such as the important Canonici collection in the Bodleian Library, have not been adequately described before, while most of the anonymous commentaries have not been listed at all. Four indexes are provided to facilitate searching the main text. Rodney M. Thomson is Emeritus Professor of Medieval History at the University of Tasmania and Honorary Research Fellow in its School of History Classics. He has published widely on books, libraries and learning in western Europe, ninth to sixteenth centuries.