BSG may refer to:
- Advanced 365 (previously Business Systems Group Ltd), an outsourced IT managed services company
- Basigin, aprotein that in humans is encoded by the BSG gene
- Bata Airport (IATA code: BSG), the second largest airport in Equatorial Guinea
- Battlestar Galactica, an American science fiction franchise created by Glen A. Larson
- Battlestar Galactica (1978 TV series), an American science fiction television series
- Battlestar Galactica (2004 TV series), military science fiction serial drama television series
- Battlestar Galactica (board game), the 2008 board game based on the 2004 television series
- Beacon Street Girls, a tween book series by Annie Bryant
- Betriebssportgemeinschaft (GDR), an organizational form of sports clubs in East Germany
- Bibliothèque Sainte-Geneviève, a library in Paris
- Birtles Shorrock Goble, an Australian pop/rock group
- Blue supergiant, supergiant stars of spectral type O or B
- Borosilicate glass, a type of glass with the main glass-forming constituents silica and boron oxide
- Bournemouth School for Girls, a grammar school located in Bournemouth, Dorset
- Brendon Small's Galaktikon, the solo album debut by Brendon Small
- British Sitcom Guide (now British Comedy Guide), a British website covering all forms of British comedy
- British Society for Geomorphology, the professional organisation for British geomorphologists
- British Society of Gastroenterology, a British professional organisation of gastroenterologists and associates
- Brotherhood of Saint Gregory, a community of friars within the Anglican communion
- Business Systems Group, an outsourced IT managed services company