An Apache revolver is a handgun which incorporates multiple other weapons, made notorious by the French underworld figures of the early 1900s known as Les Apaches.
The gun operates on the principle of a pepper-box revolver and incorporates a fold-over knuckle duster forming the grip and also a foldout knife. Because of its lack of a barrel, its effective range was very limited, but since all its component parts could be folded away, it was easily concealable inside a pocket. It was popular to leave one bullet out of the gun to prevent shooting yourself while having it concealed in a pocket or bag.
A 9mm revolver of similar design (but no official designation) was allegedly used by British commandos during World War II, though exact statistics about production numbers and technical details have as yet remained undisclosed to the general public.