The powerful goshawk (Accipiter efficax), also referred to as the greater New Caledonian goshawk, is an extinct species of bird of prey in the Accipitridae family. It was endemic to the island of New Caledonia in Melanesia in the south-west Pacific region. It was described from subfossil bones found at the Pindai Caves paleontological site on the west coast of Grande Terre. The specific epithet comes from the Latin efficax (powerful) because of its large size and robust legs.