Sir Paul Terence Callaghan GNZM FRS FRSNZ (/ˈkæləhæn/ KAL-ə-han; 19 August 1947 – 24 March 2012) was a New Zealand physicist who, as the founding director of the MacDiarmid Institute for Advanced Materials and Nanotechnology at Victoria University of Wellington, held the position of Alan MacDiarmid Professor of Physical Sciences and was President of the International Society of Magnetic Resonance.