Bodyguard of Lies is a 1975 non-fiction book on Allied military deception operations during World War II written by Anthony Cave Brown. His first major historical work, it derives its name from a wartime quote of Winston Churchill, and offers a narrative account of aspects of both the Allied and German intelligence operations during the war. The British and American governments resisted Brown's attempts to research the book. Many of the topics were still classified and he was denied access to British war records. The material in the book is predominantly based on oral testimony as well as some American records, declassified toward the end of Brown's research.

Critical reception has been mixed, initially more balanced, generally more negative with time. Contemporary historians, such as Charles B. MacDonald, praised the work – although some did comment on its length. Modern reviewers have identified inconsistencies or errors in the material, based on later declassified records. Also, some of Brown's personal conclusions have been questioned.

Bodyguard of Lies was the British-born Brown's first published book, following his career as a journalist in the United Kingdom and Australia. The work narrates Allied deception strategy on the Western Front for the years of 1943 and 1944. It particularly focuses on Operation Bodyguard, the name of which was inspired by one of Winston Churchill's wartime epigrams; "In war-time, truth is so precious that she should always be attended by a bodyguard of lies."

Brown began researching and writing Bodyguard of Lies in 1961, at a time when details of both cryptography and deception during the war were still classified. His attempts at research was resisted by the British and American governments; he was denied access to British war records and had to undertake considerable work into the 1970s to obtain US records via Freedom of Information requests. Consequently, most of the material is based on oral testimony from Second World War intelligence personnel, as well as records from the National Archives and declassified American records (although Brown says that most of the book was written before he was able to access the latter, in 1974).

Bodyguard of Lies opens with an introduction to Ultra, the codename for decrypted high-level World War II signals intelligence. It goes on to document the origins of the London Controlling Section (LCS) and the work of Dudley Clarke in the Middle East. In late 1942, Allied high command in London became aware of Clarke's successes during the North African campaign. Based on his theories of deception, the LCS was created under Colonel John Bevan and granted broad powers to plan deception strategy. The introduction finishes with a discussion of how the Allies evolved deception strategy prior to 1943, including its Double-Cross System of Allied double agents.

The second section of the book introduces the German intelligence forces, in particular Admiral Canaris and the Abwehr intelligence agency he headed. Brown discusses early deceptions, such as those surrounding Operation Torch, conducted against the Germans, and how the Abwehr struggled to decipher the information it was being fed.

The third section of the book covers Allied deceptions during 1943, in particular Operation Mincemeat. Brown introduces Plan Jael, the early revision of Operation Bodyguard, and follows Bevan's work in creating the deception plan.

The fourth section covers the events of early 1944, leading up to the Normandy landings on 6 June. In particular, Brown discusses Operation Fortitude and the fictional First US Army Group (FUSAG), a key part of Bodyguard, calling it "the greatest charade in history".