Halys may refer to:
Health-adjusted life years (HALYs), a type of disability-adjusted life year which are used in attempts to quantify the burden of disease or disability in populations
Halys River, a western name for the Kızılırmak River (Turkish: "Red River") in Anatolia
Halys (bug), a genus of stink bugs
A taxonomic synonym for the genus Gloydius, also known as Asian moccasin snakes, a group of venomous pitvipers found in Asia
Gloydius halys, also known by the names Halys viper and Halys pit viper
Quentin Halys (born 1996), French tennis player