LGM can refer to:
- Last Glacial Maximum
- Little Green Men
- Little Green Men, stereotypical portrayal of extraterrestrials
- The first pulsar was initially dubbed LGM-1 for "Little Green Men"
- LGM - silo-launched surface-attack guided-missile
- LGM-25 Titan
- LGM-25 Titan I ICBM
- LGM-25 Titan II ICBM
- LGM-30 Minuteman ICBM
- LGM-118 Peacekeeper ICBM
- Other
- LGM Luftfahrt GmbH Mannheim
- Logic Gate Matrices
- Libre Graphics Meeting
- Lovegood Mania