Biology

• Haplogroup H
  • Haplogroup H (mtDNA), human mitochondrial DNA
  • Haplogroup H (Y-DNA), human Y-chromosome DNA
• ATC code H Systemic hormonal preparations, excluding sex hormones and insulins, a section of the Anatomical Therapeutic Chemical Classification System
• Fay and Wu's H, a statistical test used in DNA analysis

Chemistry

• Hydrogen, symbol H, a chemical element
• H, code for a formulation of sulfur mustard
• H (or His), an abbreviation for the amino acid histidine

Computer science

• Language H, procedural programming language
• H or h, suffixed to denote hexadecimal in Intel-derived assembly languages
• .h, the filename extension for the C include directive called header

Linguistics

• h, the International Phonetic Alphabet symbol for a voiceless glottal fricative sound
• H or high, the high-prestige register in a diglossia

Mathematics

• H, the upper half-plane of the complex numbers
• H, the Heaviside step function
• h, impulse response in LTI system theory
• H, system function, system response, or transfer function in LTI system theory

Physics and cosmology

Planets

• H, distortion of symbol for Uranus
• h, distortion of symbol for Saturn

Other uses in science

• h-index, an author-level metric of the productivity and citation impact of the publications of a scientist or scholar

Film and TV

• H (1990 film), a 1990 Canadian film
• H (2002 film), a 2002 Korean film
• H. (2014 film), a 2014 American film by Rania Attieh and Daniel Garcia
• H (TV series), a 1998-2002 French TV series
• H, the production code for the 1964 Doctor Who serial The Reign of Terror
• H, a codename used to refer to an anonymous individual in the police procedural drama Line of Duty
• "H", the fifth episode of the sixth series of Taskmaster that aired in 2018
• The H logo used for Globo’s midday news program Jornal Hoje

Music

• h, a 1990 compilation album by Hitomi (singer)
• H, a 1980 album by Bob James (musician)
• H (Ayumi Hamasaki EP), 2002
• H (Lee Hae-ri EP), 2017
• "H." (song), a song by Tool on their 1996 Ænima album

Other media

• H (magazine)
• Revista H, a monthly Mexican men's magazine
• "H" Is for Homicide , the eighth novel in Sue Grafton's "Alphabet mystery" series, published in 1991

Trains

• H (S-train), a train service in Metropolitan Copenhagen
• H, Rockaway Park Shuttle subway service in New York
• Line H of the Buenos Aires Subte
• Tokyo Metro Hibiya Line, a subway service operated by the Tokyo Metro, labeled
• , the official West Japan Railway Company service symbol for the JR Tōzai Line and Katamachi Line