Mark Thomson is a British experimental particle physicist who took up the role of CERN Director-General in January 2026. He earned his doctorate from the University of Oxford in 1991 and joined CERN in 1994, where he worked on electroweak physics in the OPAL experiment at the Large Electron–Positron (LEP) collider.

He later moved to the University of Cambridge, where he was appointed Professor of Experimental Particle Physics in 2008.  

Thomson also contributed to Fermilab’s neutrino experiments, including MINOS and MicroBooNE, and served as one of the first co-spokespersons for the Deep Underground Neutrino Experiment (DUNE) from 2015. 

From 2018 to 2024, he served as Executive Chair of the UK Science and Technology Facilities Council (STFC), representing the UK on the CERN Council and other international bodies. 

Thomson is author of the textbook Modern Particle Physics (2013), aimed at final-year undergraduate students and first-year graduate students, which has been widely adopted internationally.