It is with great sadness that we announce the passing of Sir Joseph John Thomson, OM, FRS, an English physicist and Nobel laureate in physics. He passed away on 30th August 1940, aged 83. Born in 1856 in Manchester, England, Thomson was a mathematical genius who attended Owens College at the age of 14 to begin his scientific studies. His studies would take him to Cambridge University, where he discovered the electron in 1897. This discovery would revolutionize the world of physics, and would lay the foundation for the development of television, radio, radar and vacuum tubes. He was awarded the Nobel Prize in 1906 for his work. He went on to develop the motion of charged particles in electric and magnetic fields (now known as the "Thomson Problem") and later invented the mass spectrometer which would become a critical tool for atomic and molecular physics. Thomson was knighted in 1908 for his contributions to physics and was named the Cavendish Professor of Physics at Cambridge University in 1918. Thomson's research and discoveries fundamentally changed the world of physics, and his vision and leadership helped establish the Cavendish Laboratories as one of the most influential centres of scientific research in the world. He was an inspiration to many students who went on to become renowned scientists in their own right. We will remember Thomson for his leadership and research that has had a lasting impact on the scientific world.