MGO may refer to:

Science and technology

• Magnesium oxide (chemical formula MgO)

• Methylglyoxal, an organic compound

• Marine gas oil, a fuel oil

Other uses

• Master-General of the Ordnance, British military position before 1855

Metal Gear Online or MGO, a series of online modes throughout the Metal Gear series

Metal Gear Online 1, the online mode for Metal Gear Solid 3: Subsistence

• Metal Gear Online Portable Ops, the first expansion of the mode in Metal Gear Solid: Portable Ops

• Metal Gear Online Portable Ops Plus, the second expansion for the mode in Metal Gear Portable Ops Plus

  Metal Gear Online 2, the online mode for Metal Gear Solid 4: Guns of the Patriots and later as Metal Gear Online

• Metal Gear Online Peace Walker, the online mode for Metal Gear Solid: Peace Walker

• Metal Gear Online 3, the online mode for Metal Gear Solid V: The Phantom Pain

eo:MGO