The initialism GMC can mean either:

• GMC, a division of General Motors formerly named "GMC Truck" and an acronym for "Grabowski Motor Company"
• General Medical Council (of the United Kingdom)
• Greater Manchester County
• Genetically Modified Crop
• Giant Molecular Cloud
• Global Motion Compensation used by video codecs
• Gebrüder Märklin & Cie, a German model railway manufacturer, see Märklin
• GNU Midnight Commander, a file manager for Unix-like systems