Hitler's Pope is a book published in 1999 by the British journalist and author John Cornwell that examines the actions of Eugenio Pacelli, who became Pope Pius XII, before and during the Nazi era, and explores the charge that he assisted in the legitimization of Adolf Hitler's Nazi regime in Germany, through the pursuit of a Reichskonkordat in 1933. The book is critical of Pius' conduct during the Second World War, arguing that he did not do enough, or speak out enough, against the Holocaust. Cornwell argues that Pius's entire career as the nuncio to Germany, Cardinal Secretary of State, and Pope, was characterized by a desire to increase and centralize the power of the Papacy, and that he subordinated opposition to the Nazis to that goal. He further argues that Pius was antisemitic and that this stance prevented him from caring about the European Jews.
Various commentators have challenged the book's leading ideas, or challenged factual assertions contained within it. Holocaust historian Martin Gilbert credits Pius XII with various actions which saved Jews, and notes that the Nazi security forces referred to him as the "mouthpiece of the Jewish war criminals". Pius XII maintained links to the German Resistance and in the assessment of historian Frank J. Coppa writing for the Encyclopædia Britannica, Cornwell's depiction of Pius XII as antisemitic lacks "credible substantiation".
The author has been praised for attempting to bring into the open the debate on the Catholic Church's relationship with the Nazis, but also accused of making unsubstantiated claims and ignoring positive evidence. The author has moderated some of his allegations since publication of the book. In 2004, Cornwell stated that Pius XII "had so little scope of action that it is impossible to judge the motives for his silence during the war, while Rome was under the heel of Mussolini and later occupied by Germany...But even if his prevarications and silences were performed with the best of intentions, he had an obligation in the postwar period to explain those actions". He similarly stated in 2008 that Pius XII's "scope for action was severely limited", but that "[n]evertheless, due to his ineffectual and diplomatic language in respect of the Nazis and the Jews, I still believe that it was incumbent on him to explain his failure to speak out after the war. This he never did." In 2009 he described Pacelli as effectively a "fellow traveller" of the Nazis.