Alan Andrew Watson, FRS, (born 26 September 1938 in Edinburgh) is a physicist and an emeritus professor at the University of Leeds, England.

The work there led to the best estimates of the energy spectrum, mass composition and arrival direction distribution of cosmic rays available at that time, and was regarded as the premier project in the field for about 15 years.

He was the UK Principal Investigator for a project (SPASE) carried out at the South Pole, jointly with collaborators from the University of Delaware, USA, which ran from 1987 to 1994.

Initially, the aim of this work was to look for gamma-rays from the supernova, SN1987A, but it broadened in scope through collaboration with the pioneering AMANDA phase of the IceCube neutrino project, targeting the mass composition of cosmic rays above 1014 eV.

[3] Watson was instrumental, along with J W Cronin, in the creation of the Pierre Auger Observatory in Argentina (begun 1999) which has gathered the data that led to major discoveries in cosmic-ray astronomy, notably providing evidence that the highest energy particles are nuclei of intermediate mass and that there are significant anisotropies in the distribution of arrival directions.