Statista 149 country reports
Sage Data (click on the geography tab)
CIA World Fact Book - information on the history, people, government, economy, geography, communications, transportation, military, and transnational issues for 267 world entities.
NationMaster - a massive central data source and a handy way to graphically compare nations. NationMaster is a vast compilation of data from such sources as the CIA World Factbook, UN, and OECD.
OECD iLibrary - Organisation for Economic Co-operation and Development
United Nations Statistical Yearbook - annual compilation of a wide range of international economic, social and environmental statistics on over 200 countries and areas, compiled from sources including UN agencies and other international, national and specialized organizations.
U.S. Census Bureau Statistics - List of international statistical agencies
World Bank Data - data about development in countries around the globe, together with other datasets cited in the data catalog
World Health Organization - access to data and analysis for monitoring the global health situation