Siamon Gordon FRS FMedSci (born 29 April 1938) is a British pathologist.
[2] He is Glaxo Wellcome Professor Emeritus of Cellular Pathology at the University of Oxford.
[7] Gordon is noted for his work on the phenotypic and functional diversity of macrophages.
He began his studies on macrophages while in the laboratory of Zanvil Cohn at Rockefeller University in 1966.
Upon his move to the Sir William Dunn School of Pathology at University of Oxford in 1976 he continued this work and identified the pan-macrophage marker F4/80.