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

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

Croatian Labourists – Labour Party (Croatian: Script error: No such module "Lang".), a political party in Croatia
Headline, a text indicating the nature of the article below it
Heilongjiang, a province of China (Guobiao abbreviation HL)
Higher Level, a level of course difficulty in the International Baccalaureate Diploma Programme
Hit list (disambiguation)
HL v United Kingdom a law case at the European Court of Human Rights, sometimes known as the HL case.
Hong Kong Higher Level Examination, a standardized examination from 1979 to 1992
House of Lords, the upper house of the Parliament of the United Kingdom
Hueiyen Lanpao, a Meitei-English bilingual newspaper of Manipur