GEF or Gef may refer to:
- Gef, a supposed talking mongoose from the Isle of Man
- Global Education Futures, a European NGO focused on global transformation of education
- Global Enrichment Foundation, a Canadian humanitarian organization
- Global Environment Facility, an intergovernmental environmental organizations
- Global Equality Fund, of the United States Department of State
- Green European Foundation, a European political foundation
- Graphical Editing Framework, a software framework
- Greek Expeditionary Force (Korea), during the Korean War
- Greif, Inc., an American manufacturing company
- Guanine nucleotide exchange factor