Porter Airlines is a regional airline headquartered at Billy Bishop Toronto City Airport on the Toronto Islands in Toronto, Ontario, Canada. Porter operates regularly scheduled flights between Toronto and locations in Canada and the United States using Canadian-built Bombardier Dash-8 Q 400 turboprop aircraft.

Porter's operation at the Toronto airport was launched in 2006 after some controversy. A planned bridge to the airport was cancelled in 2003, leading to lawsuits between the airline and the City of Toronto. The airline bought the island airport terminal and evicted rival airline Air Canada Jazz from the airport. Despite opposition from nearby community groups, Porter has expanded its operations since 2006, adding more destinations and planes. Porter opened a new, larger, passenger terminal at the island airport in March 2010. In 2008, Porter got a 4-star Skytrax rating, the only Canadian airline to do so