The Lockheed XPB-3, later designated XFM-2, (PB - Pursuit, Biplace / FM - Fighter, Multi-seat), was a proposed American heavy fighter aircraft, developed by the Lockheed Corporation during the mid-1930s. Intended as a heavy fighter and bomber destroyer for operation by the United States Army Air Corps, it failed to win a contract for construction of a prototype, the Bell YFM-1 Airacuda being preferred.