Horizon Air Industries, Inc., operating as Horizon Air, is a regional airline based in SeaTac, Washington, United States. Horizon Air and its sister carrier Alaska Airlines are subsidiaries of Alaska Air Group and all Horizon-operated scheduled flights are marketed and sold by Alaska Airlines. Planes operated by Horizon are now co-branded as "Alaska Horizon" in recognition of the Horizon brand and to differentiate aircraft from those operated by Alaska's other regional airline partner, SkyWest Airlines.

Horizon Air was once the eighth largest regional airline in the USA, serving 42 cities in the United States and Canada. It was purchased by Alaska Air Group in November 1986 and continued to fly as a separately branded airline until 2011, when its public brand was retired in favor of the Alaska brand.

Horizon Air was formed in May 1981 by Milt Kuolt, and started operations on September 1, 1981, with three Fairchild F-27 aircraft. Its headquarters were in an area that is now within SeaTac, Washington.

Horizon Air's first route was from Yakima to Seattle and one week later, Pasco to Seattle. The general offices of Horizon Air were operated out of an old house behind Sea-Tac airport. Horizon acquired Air Oregon on June 17, 1982, after both airlines were losing hundreds of thousands of dollars monthly, in order to consolidate and reduce their operating deficit. Horizon agreed to purchase Transwestern Airlines of Utah in September 1983, once again to try to reduce operating deficit of the airline. A single Fokker F28 Fellowship twin jet, purchased in July 1984 from an African carrier, was the first jet owned by Horizon Air; however, their first jet was a wet leased Douglas DC-9-10. Additional Fokker F28s were leased from USAir during the mid-1990s. An initial public offering occurred in 1984 to secure operating capital, which after only one profitable year since founding, was needed to keep the airline afloat.

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