The Allied Coalition that defeated the Axis Powers in World War Two consisted of dozens of nations. The major Allies were France, the United Kingdom, China, the Soviet Union, and the United States. Other Allies included Australia, Canada, New Zealand, India and South Africa from the British Commonwealth. Brazil, Iran, Iraq, Ethiopia, the Philippines, Bolivia, Colombia, Costa Rica, Cuba, the Dominican Republic, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, and Panama all declared war on the Axis as well and gave varying, but limited, support to thw war efforts. Finally, many nations that were overrun and conquered by the Axis continued to fight on as partisans on the ground and through Governments in Exile politically. These Allies included Poland, Belgium, Czechoslovakia, Greece, Luxembourg, the Netherlands, Norway, Yugoslavia, and Romania after 1944 (http://www.nationmaster.com/encyclopedia/Allies).
The members of the Axis powers were far fewer. The major members of the Axis were Germany, Japan, and Italy. The Black Sea states of Bulgaria, Hungary, and Romania were lesser members. Puppet states under control of or conquered by the Axis powers were nominally members of the alliance, but gave little actual support. These included Manchukuo, Slovakia, Croatia (carved out of Yugoslavia by force), Siam and Vichy France. In addition, Finland joined the Axis for support after being invaded by the Soviets (http://www.nationmaster.com/encyclopedia/Axis-powers).
This looks like a huge advantage for the Allied forces in sheer numbers and, of course, it was. But the rosters at the end of the war were different from those that began the war. The rundown above noted that Hungary switched sides in 1944. Other changes occurred along the way as well. At the beginning of the war in 1939, it was just France, Britain and Poland against the Germans and Italian. The rest of Europe was trying to cling to their neutral...