Ventriloquism, or ventriloquy, is an act of stagecraft in which a person (a ventriloquist) changes his or her voice so that it appears that the voice is coming from elsewhere, usually a puppeteered "dummy". The act of ventriloquism is ventriloquizing, and the ability to do so is commonly called in English the ability to "throw" one's voice.

Originally, ventriloquism was a religious practice. The name comes from the Latin for to speak from the stomach, i.e. venter (belly) and loqui (speak). The Greeks called this gastromancy (Greek: εγγαστριμυθία). The noises produced by the stomach were thought to be the voices of the unliving, who took up residence in the stomach of the ventriloquist. The ventriloquist would then interpret the sounds, as they were thought to be able to speak to the dead, as well as foretell the future. One of the earliest recorded group of prophets to utilise this technique was the Pythia, the priestess at the temple of Apollo in Delphi, who acted as the conduit for the Delphic Oracle.