The 1906 Summer Olympics or 1906 Intercalated Games were discounted ex post facto by the IOC. All medals awarded during these games have not since been counted officially on total medal counts.
These games were cancelled due to the World Wars. The 1916 Summer Olympics were cancelled due to the onset of WWI; both the Summer and Winter Olympics of 1940 and 1944 were cancelled due to WWII.
Some summer events were held by the IOC in celebration of its Jubilee in Lausanne, despite the war that cancelled the 1944 Summer Olympics, at the Jubilee Celebrations of the IOC.