Norris J. Lacy (born 1940) is an American scholar focusing on French medieval literature. He is the Edwin Erle Sparks Professor Emeritus of French and Medieval Studies at the Pennsylvania State University. He is a leading expert on the Arthurian legend and has written and edited numerous books, papers, and articles on the topic.
He received his Ph.D. from Indiana University and has held teaching positions at the University of Kansas, the University of California, Los Angeles, and Washington University in St. Louis. He has served as president of the International Arthurian Society. With Geoffrey Ashe he wrote The Arthurian Handbook, and he edited The Arthurian Encyclopedia and its successor, The New Arthurian Encyclopedia, a standard reference book for Arthurian works. He also oversaw the first complete English translation of the French Vulgate and Post-Vulgate Cycles, released as the five-volume Lancelot-Grail: The Old French Arthurian Vulgate and Post-Vulgate in Translation.