HL

HL may refer to:

In arts and entertainment

 * Half-Life (series), a video game series by Valve
 * Half-Life (video game), the first game in that series
 * Horseland, an online community and virtual game
 * Harry Styles and Louis Tomlinson, part of the popular boyband One Direction known as HL when referred to together

Businesses

 * Hangars Liquides, an electronic music label
 * Hargreaves Lansdown, a British investment company
 * Hitachi-LG Data Storage, an optical disc drive manufacturer
 * Hogan Lovells, an international law firm
 * Houlihan Lokey, an international investment bank
 * Hovedstadens Lokalbaner, a Danish local railway company

In linguistics

 * $⟨hl⟩$, a Latin-script digraph
 * Reduction of /hl/ to /l/ in Old/Middle English
 * Voiceless alveolar lateral fricative, a sound sometimes represented as $⟨hl⟩$

Science, technology, and mathematics

 * HL gas, a mixture of sulfur mustard and lewisite
 * Half-life, in nuclear physics
 * Hectolitre, a unit of volume
 * Hessdalen light, an unexplained light seen in Norway
 * Hodgkin's lymphoma, a highly treatable hematological malignancy ("blood cancer")
 * Hotline, a telecommunications link
 * Hydrogen line, a spectral line
 * Hypotenuse Leg, a postulate of geometry
 * HL, an amateur radio call sign prefix in South Korea

Other uses

 * Hueiyen Lanpao, a Meitei-English bilingual newspaper of Manipur
 * Croatian Labourists – Labour Party (Croatian: Hrvatski laburisti - Stranka rada), a political party in Croatia
 * Headline, a text indicating the nature of the article below it
 * Heilongjiang, a province of China (Guobiao abbreviation HL)
 * Hit list (disambiguation)
 * House of Lords, the upper house of the Parliament of the United Kingdom
 * Higher Level, a level of course difficulty in the International Baccalaureate Diploma Programme
 * Hong Kong Higher Level Examination, a standardized examination from 1979 to 1992