WestAir Commuter Airlines, was a U.S.-based regional airline formed when Stol Air Commuter changed its name in 1978 to WestAir Airlines; it was renamed WestAir Commuter Airlines in 1986. One of the founders was Maurice J. Gallagher, Jr., who later acquired Allegiant Air. WestAir subsequently became a United Express air carrier via a code sharing agreement with United Airlines. It was headquartered in Fresno, California and was controlled by WestAir Holding, Inc. WestAir was sold to Mesa Air Group in 1992.

United Express is the brand name for the regional branch of United Airlines, under which five individually owned regional airlines operate short- and medium-haul feeder flights.