The Brain from Planet Arous

The 1957 film The Brain from Planet Arous features aliens from outer space that possess the bodies of Earthlings because that's much cheaper than building an alien. An evil brain named Gor, a criminal mastermind from the planet Arous, wants to take over Earth by possessing the body of an atomic scientist. Meanwhile, a cop named Vol, also from the planet Arous, pursues Gor by taking possession of a dog. Sic 'em! (Thanks, WTM!)