The AgustaWestland AW139 is a 15-seat medium sized twin-engined helicopter manufactured by AgustaWestland. Originally designed and developed jointly by Agusta and Bell Helicopters and marketed as the Agusta-Bell AB139, it was redesignated the AW139 when Bell withdrew from the project.

The AW139 has become one of AgustaWestland's most influential products; it has been subsequently developed into two enlarged medium-lift helicopters, the military-orientated AW149 and the AW189 for the civil market.

The AB139 is a conventional layout twin-engined transport helicopter. It has a five-bladed fully articulated main rotor with a titanium hub and composite blades and a four-bladed tail rotor. It is fitted with a retractable tricycle landing gear. It is flown by a crew of two pilots, with up to 15 passengers accommodated in three rows of five. It is powered by two Pratt & Whitney PT6C turboshaft engines. The helicopter is being marketed for use in a number of roles including Law Enforcement/Emergency Medical Service, Executive Transport, Search and Rescue, Maritime and Offshore Oil Operations.