ODG
ODG can refer to:

.odg, the file extension for an OpenDocument drawing file
Ontario Drive and Gear Limited, a former company specializing in amphibious vehicles; now part of ARGO
Old Dungeon Ghyll, Lake District, England, popular with walkers and climbers
Objective difference grade, a perceived quality in digital audio
Olive drab green, a color used in military clothing and equipment
Overseas Development Group, a fictional UK espionage agency that James Bond works for in Carte Blanche by Jeffery Deaver.