Most of us know perfectly well what we ought to do; our trouble is that we do not want to do it.

J. Peter Marshall may refer to:
Peter Marshall (author) (born 1946) British author whose works include Demanding The Impossible: A History of Anarchism and Europe's Lost Civilization
Sir Peter Marshall (diplomat) British diplomat and former Commonwealth Deputy Secretary-General (1983-88)
Peter Marshall (police commissioner) (born c. Marshall (Peter James Marshall born 1933) historian Emeritus Rhodes Professor of Imperial History at King's College London
Peter Paul Marshall (1830–1900) Scottish civil engineer painter and partner in Morris Marshall Faulkner & Co.