Who are the main leaders of Buddishm?

Buddhism takes different forms in different countries, and amongst different sects. Tibetan Buddhism recognizes the Dalai Lama as the spiritual and political leader of Tibet. There are also Rimpoches, who are lamas who, through lifetimes of Buddhist practice, have reached an understanding of the true nature of reality deep enough that they can identify who they were in their past lives - always another accomplished lama. Rimpoches have power because they are thought to have a deeper understanding of the Buddha's teaching. For the most part, teachers and accomplished lamas are the leaders.