International Union for Conservation of Nature and Natural Resources Red List of Endangered Species
The IUCN's Red List of Endangered Species allows users to create lists and summaries of endangered or threatened species by taxonomy, extent of threat, and/or geography (e.g. countries, maritime regions).
United Nations Environmental Programme GEO Data Portal
To quote the website, "[the] GEO Data Portal is the authoritative source for data sets used by UNEP and its partners in the Global Environment Outlook GEO) report and other integrated environment assessments. Its online database holds more than 400 different variables, as national, subregional, regional and global statistics or as geospatial data sets (maps), covering themes like Freshwater, Population, Forests, Emissions, Climate, Disasters, Health and GDP." Researchers are able to download the data in multiple formats.