• Happy Hustle High, a manga series by Rie Takada, originally titled "H3 School!"
• H3 (film), a 2001 film about the 1981 Irish hunger strike
• h3h3Productions, styled "[h3]", a satirical YouTube channel

• Triatomic hydrogen (H₃), an unstable molecule
• Trihydrogen cation (H₃⁺), one of the most abundant ions in the universe
• Tritium (Hydrogen-3, or H-3), an isotope of hydrogen
• ATC code H03 Thyroid therapy, a subgroup of the Anatomical Therapeutic Chemical Classification System
• British NVC community H3, a heath community of the British National Vegetation Classification system
• Histamine H₃ receptor, a human gene
• Histone H3, a component of DNA higher structure in eukaryotic cells
• *h₃, one of the three laryngeals in the reconstructed Proto-Indo-European language
• Hekla 3 eruption, a huge volcanic eruption around 1000 BC

• <h3></h3>, the level-3 HTML heading markup element
• HTTP/3, the third revision of a protocol for the World Wide Web
• Socket H3, the common name of the LGA 1150 CPU socket

Air and space edit

• H3 (rocket), an expendable launch system under development by Japan Aerospace Exploration Agency
• Harbour Air Seaplanes (IATA code), a Canadian charter airline
• H-3 Air Base, former Iraqi Air Force base in western Iraq
• H-3 Sea King, a United States Navy helicopter
• Standard H-3, an improved version of the 1916 Standard H-2 aircraft

Automobiles edit

• Brilliance H3, a Chinese compact sedan
• Haval H3, a Chinese compact SUV
• Huansu H3, a Chinese compact MPV
• Hummer H3, an American mid-size SUV

Ships edit

• USS H-3 (SS-30), a 1914 United States Navy H-class submarine
• HMS Grenville (H03), a 1935 British Royal Navy destroyer
• HMS H3, a 1915 British Royal Navy H-class submarine
• H3, a yacht build by Oceanco

Rail edit

• H3 series of METRORail tramways in Houston
• GNR Class H3, a class of British steam locomotives

Roads edit

• H3 Monks Way, a road part of the Milton Keynes grid road system, United Kingdom
• Interstate H-3, a highway in Hawaii

• H3 (classification), a para-cycling classification
• H3, an 18th-century marine chronometer by John Harrison
• H3, a type of automotive halogen lamp
• H3 (pyrotechnics), a pyrotechnic composition
• H3 Hardy Collaboration Architecture, a firm started by Hugh Hardy
• H3 Pharmaceutical Chemistry, an advanced subject for GCE A-level students in Singapore
• DSC-H3, a 2008 Sony Cyber-shot camera
• Hash House Harriers, an international group of non-competitive running, social and drinking clubs
• H3 (Kuwait), an archaeological site
• H3 Entertainment, a subsidiary of the film industry company The H Collective

• 3H (disambiguation)
• HHH (disambiguation)
• Triple H (disambiguation)