FSG can refer to:
Finite state grammar Falling sand game Fishersgate railway station, a railway station in Sussex, England Fluorosilicate glass Focal segmental glomerulosclerosis Free Spirit Gathering, an American Pagan and Pantheist event United States Federal Sentencing Guidelines
Organizations Fellow of the Society of Genealogists Florida State Guard, active during World War II Folkestone School for Girls, in England Fortress Study Group, a British historical charity Free Standards Group, a defunct open-source standards organization
Businesses Facility Solutions Group, an American electrical engineering company Farrar, Straus and Giroux, an American book publisher Fenway Sports Group, an American sports investment company Flensburger Schiffbau-Gesellschaft, a German shipbuilder Frontier Services Group, a Hong Kong–based, Africa-focused security, aviation, and logistics company