Wow Air, stylized as WOW air, was an Icelandic ultra low-cost carrier operating between 2012 and 2019. The airline was headquartered in Reykjavík and based at Keflavík International Airport. It flew between Iceland and the rest of Europe and North America, and also flew to India as part of a wider plan to expand in Asia. The airline abruptly ceased operations on 28 March 2019, when its operating company WOW air hf. went out of business.

The airline's assets were acquired by United States–based holding company USAerospace Associates, which announced in 2019 and 2020 that the airline was relaunching service; however, flights did not commence, and the media was unable to independently verify the company's statements about its business plans or find evidence of an application for an air operator's certificate.

Iceland's geographic position has made it an attractive stopover point for flights across the Atlantic. In the 1960s, flag carrier Icelandair established a stopover scheme to encourage tourism that continues to this day. Icelandic Airlines, also known as Loftleiðir and remembered by the nicknames "Hippie Airline" and "Hippie Express", also used this approach along with a number of expense-lowering measures to become the first low-cost transatlantic carrier before it merged to form Icelandair. The collapse of the króna due to the Icelandic financial crisis in 2008 and the publicity brought by the 2010 eruption of Eyjafjallajökull to its natural features led to a significant rise in tourism there.

Wow Air was founded by Icelandic entrepreneur Skúli Mogensen, who previously had an extensive business background largely in technology and telecoms in Iceland, Europe, and North America. The sole owner of Wow Air was Titan, an investment company owned by Mogensen, who was the company CEO and sat on the five-person board of directors. Mogensen cited a gap in the low-cost aviation market with regards to Iceland, and aimed to make it a major international transit point, repeatedly stating throughout that airline's history that he wanted Iceland to become "the Dubai of the north". According to him, the airline's name was chosen to signify his feelings toward Iceland and also because it reads "MOM" when the letters are turned upside down. Booking was opened 24 November 2011, with the airline planning to serve 12 destinations in Europe upon its operational launch the next summer.

The airline's first service, from Keflavík to Paris Charles de Gaulle, was flown on 31 May 2012. In October 2012, Wow Air acquired Iceland Express's operations and network. Iceland Express operated to several destinations in Europe and North America using leased equipment. At the end of October 2012, following the acquisition of its operations, flights to Gatwick and Copenhagen saw frequency increases, services to Berlin, Kaunas (which was later dropped again), Salzburg and Warsaw had begun.

The airline carried over 400,000 passengers in 2013 and reached its one millionth passenger in December 2014.

From 2015, Wow Air started expanding into North America, serving first the U.S., then Canada starting in May 2016. Flights to Los Angeles and San Francisco began in June 2016 using two Airbus A330-300 planes leased from Air Europa. Wow Air's annual passenger capacity more than doubled in 2016 to over 1.6 million, from approximately 740,000 in 2015.

In 2017, Wow Air was accused of spreading false claims through churnalism, after several media outlets reported its claim that it would fly passengers from London Stansted to New York for £99, which it said was below cost. A flight leg priced at £99 was only available as part of a significantly more expensive return flight.