Ivan Todorov Todorov (born 26.10.1933) was a Bulgarian theoretical physicist and a member of the Bulgarian Academy of Sciences (1974). He was born in Sofia. He graduated from the University of Sofia (1956). In 1956 — 58 he worked at the Institute of Physics of the Bulgarian Academy of Sciences, and in 1958 — 71 at the Joint Institute for Nuclear Research (Dubna). From 1971 he was at the Institute of Physics of the Bulgarian Academy of Sciences and professor at the University of Sofia.
His work was in the fields of quantum field theory and elementary-particle physics. Together with A. A. Logunov and others he developed the majorisation technique in perturbation theory (1962) and proved the equality of the differential scattering cross sections of a particle and an antiparticle (1963).