International Union for Conservation of Nature and Natural Resources Red List of
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 450 different variables at national, subregional, regional and global data or as geospatial datasets (maps)". The data here cover a wide range of themes and topics, including biodiversity and threatened species.