OMG may refer to:
- Oh My God, Oh My Goodness, or Oh My Gosh, a common abbreviation used in SMS, Instant Messaging and other internet communication.
- omg!, a celebrity news and gossip Web site run by Yahoo.com
- OMG! Magazine, a news, entertainment and lifestyle magazine serving gay, lesbian and trans-gender audiences in print and online.
- "OMG (Oh My Gosh)", a song by Sabrina Washington
- "OMG" (song), a song by Usher featuring will.i.am
- OMGcon, an annual anime and gaming convention in Paducah, Kentucky, U.S.
- OMG particle, an ultra-high-energy cosmic ray observed on the evening of 15 October 1991
- OMG! Ubuntu!, on line tech magazine
- Object Management Group, the consortium responsible for CORBA (Common Object Request Broker Architecture), Unified Modeling Language (UML), and Model-Driven Architecture (MDA)
- Old Melbourne Gaol, an old prison, now museum of law & crime in Melbourne, Australia
- Old Man Gloom, a band originally from Santa Fe, New Mexico
- Old Mutual Group, an international insurance company
- Olympiad of Misguided Geeks, a programming contest on The Daily WTF
- Omega
- OM Group, a chemistry firm based in Cleveland, Ohio, stock symbol NYSE:OMG
- One Man Gang, George Gray, former professional wrestler also known as Akeem
- OpenMG file format's Filename extension
- Operation Market Garden, an Allied plan in World War II
- Operational manoeuvre group, a Soviet organisational maneuver warfare concept
- Outlaw Motorcycle Gangs
- Oh My God (2012 film)