BCG (plural BCGs)
- Bacillus of Calmette and Guérin, a vaccine for tuberculosis developed by Albert Calmette and Camille Guérin
- (US, military slang) Initialism of birth control glasses.
- (astronomy) Initialism of brightest cluster galaxy.
- (astronomy) Initialism of blue compact galaxy.
- (blue compact galaxy): BCD
Bacillus of Calmette and Guérin