The main stakeholders who are concerned about poverty in the world are, of course, the poor themselves. But as they are not organized, we do not see them in that way.
As far as organizations go, a major stakeholder is the group of nongovernmental organizations (NGOs) that is concerned with this issue. Groups like the Gates Foundation and UNICEF are dedicated to fighting against poverty, its causes, and/or its effects.
A second group of stakeholders is made up of companies whose businesses are centered around creating products or services that can be used by poor people. These would include firms that market low-cost mobile phones to poor people or those in less developed countries that are trying to create ways for the poor to use those mobile phones as ways of giving and receiving payments.
Both of these groups of stakeholders are interested in reducing poverty worldwide.