HM or hm may refer to:
Arts and entertainment
- HM (magazine), a Christian hard rock magazine
- Hidden Machine, a type of item in Pokémon
Businesses
- H&M, a Swedish clothing company
- Hindustan Motors, an automobile manufacturer of India
- Air Seychelles (IATA airline code)
Other uses
- Heard Island and McDonald Islands (ISO 3166 digram and FIPS PUB 10-4 territory code)
- .hm, the Internet country code top-level domain ostensibly for the above
- Hectometre, hm, an SI unit of length
- Henry Molaison, aka Patient H.M., a man with anterograde amnesia
- Her Majesty or His Majesty, a form of address for the monarch of the United Kingdom and Commonwealth realms
- Hindley–Milner type system, in mathematics
- Hospital corpsman, in the United States Navy
- Sisters of the Holy Humility of Mary's postnominal initials