GCR may refer to:
- Galactic cosmic ray, the high-energy particles that flow into our solar system from far away in the galaxy
- Gas cooled reactor, a nuclear reactor type
- Gateshead Community Radio, a former recurring RSL that broadcast to Gateshead in the 1990s.
- General Chinese Romanization, a cross-dialectal spelling system devised by Chao Yuen Ren
- Geological Conservation Review
- Ghost-canceling reference, a special television signal that helps reduce the effects of multipath ("ghosting")
- Global Competitiveness Report
- Glucocorticoid receptor, a ligand-activated transcription factor that binds with high affinity to cortisol and other glucocorticoids
- Graduate Common Room, a term for a postgraduate student organisation, sometimes used in collegiate universities in place of the more common MCR
- Grand Central Railway, an open-access United Kingdom railway company
- Great Central Railway, a railway company and former main line in the United Kingdom
- Great Central Railway (preserved), the preserved railway running on part of the old main line
- Grey component replacement, a topic in desktop publishing
- Group Code Recording, a set of encoding methods for magnetic media (floppy disks, etc.)
- Groupe Communiste Révolutionnaire, the French name for the Lebanese Revolutionary Communist Group
- Guildford Campus Radio, the former name of student radio station GU2