HBT is a three-letter initialism that can mean:
- Holistic Body Training
- Handelsschule Berliner Tor
- Holy Bible Trivia
- Holme Bait and Tackle
- Healthcare Benefit Trust
- Heritage Bank & Trust
- Heterojunction Bipolar Transistor
- Happy Birthday Tamara
- Herringbone twill, a type of cloth
- Hostage Barricade Team
- Houston Belt and Terminal Railway
- HydroBall Technics
- Hydrogen Breath Test
- HBT, 5,5'-hydrazinebistetrazole, an experimental explosive material that is more environmentally friendly than current methods.
- Homosexual, Bisexual, and Transsexual (see LGBT)
- Hanbury Brown and Twiss effect, a variety of correlation and anti-correlation effects in the intensities received by two detectors from a beam of particles
- Harry B. Thompson Middle School
- Hunter's Bog Trotters, an irreverent Scottish Cross Country, Road, and Fell Running Club based in Edinburgh
- HBT (agar), human blood bilayer-Tween 80 agar, used in microbiology as a selective differential human blood bilayer media for isolation of Gardnerella vaginalis