|A leader who is actually a follower. Many national leaders are in secret thrall to powerful forces who established their 'power'.|
Interestingly, Wikipedia has nothing much to say on the matter. The phrase "puppet leader" occurs about 35 times in English wikipedia, but the corresponding page redirects to puppet state, which is quite a different concept.
This term could be applied to a lot of modern politicians, with varying degrees of applicability. In Confessions of An Economic Hitman, John Perkins describes how the IMF and World Bank routinely install puppets in "developing nations" so that they can be manipulated to benefit multinational corporations. He names Omar Torrijos and Jaime Roldós Aguilera as two examples of national leaders who could not be corrupted. Both died in fiery plane crashes.