GCG may refer to:
- GCG (software), A sequence analysis software package.
- GCG, A British online magazine about video games, comics and gadgets.
- Gallocatechin gallate, a flavonol
- Global Church of God, a Sabbatarian church based in England
- Glucagon, a protein
- Government College for Girls, a college in Chandigarh, Punjab, India
- Gwaun-Cae-Gurwen, a village in Neath Port Talbot, south Wales
- Graduate-Consulting-Group, biggest graduate student consulting group based in Victoria, Melbourne.
- one of the codons coding for alanine
- a trinucleotide whose mutation in the PABPN1 human gene leads to autosomal dominant oculopharyngeal muscular dystrophy (OPMD) disease