John Ellis (physicist, born 1946)

Jonathan Richard "John" Ellis CBE FRS HonFInstP (born 1 July 1946) is a British-Swiss theoretical physicist.

After completing his secondary education at Highgate School, he attended King's College, Cambridge from 1964, earning his PhD in theoretical (high-energy) particle physics in 1971, after having spent the academic year 1970/71 as a visiting student at CERN. After one-year post-doc positions in the SLAC Theory Group and at Caltech, he went back to CERN in 1973, first as a research fellow and from 1974 as a staff member, where he remained until he reached the fixed retirement age of 65. Since 2010 Ellis is Clerk Maxwell Professor of Theoretical Physics at King's College London, but continues to work at CERN holding a visiting scientist appointment.

Ellis' activities at CERN have been wide-ranging in addition to his research. He was twice Deputy Division Leader for the theory ("TH") division, and served as Division Leader for 1988–1994. He was a member of the committees that selected experiment at the LEP and LHC accelerators and participated in early studies of possible future colliders such as CLIC and FCC. In the early 2000s he advised successive CERN Directors-General on relations with non-member states. He was also the first chair of CERN's Equal Opportunities Advisory Panel.