Sir Ian Kershaw FBA is an English historian whose work has chiefly focused on the social history of 20th-century Germany. He is regarded by many as one of the world's leading experts on Adolf Hitler and Nazi Germany, and is particularly noted for his biographies of Hitler. He was the leading disciple of the German historian Martin Broszat, and until his retirement, he was a professor at the University of Sheffield. Kershaw has called Broszat an "inspirational mentor" who did much to shape his understanding of Nazi Germany. Kershaw served as historical adviser on numerous BBC documentaries, notably The Nazis: A Warning from History and War of the Century. He taught a module titled "Germans against Hitler".