Hz is the International Standard symbol for Hertz, the unit of frequency
HZ may also stand for:
- Habitable zone, the distance from a star where a planet can maintain Earth-like life
- Hamilton Zoo, in New Zealand
- Hazard, a situation that poses a level of threat
- Herero language, ISO 639 alpha-2
- Herpes Zoster, shingles
- Holden HZ, automobile produced by General Motors Holden in the late 1970s
- Hrvatske Željeznice, the Croatian national railway (HŽ)
- HZ (character encoding)
- SAT Airlines IATA airline designator
- Saudi Arabia aircraft registration code
- Hans Zimmer
- Horizons: Empire of Istaria