The Southern Television broadcast interruption was a broadcast signal intrusion that occurred on 26 November 1977 in parts of southern England in the United Kingdom. The audio of a Southern Television broadcast was replaced by a voice claiming to represent the 'Ashtar Galactic Command', delivering a message instructing humanity to abandon its weapons so it could participate in a 'future awakening' and 'achieve a higher state of evolution'. After six minutes, the broadcast returned to its scheduled programme.

Subsequent investigations showed that the Hannington transmitter of the Independent Broadcasting Authority had rebroadcast the signal from a small but nearby unauthorised transmitter, instead of the intended source at Rowridge transmitting station. The hoaxer was never identified.

The event prompted hundreds of telephone calls from concerned members of the public, and was widely reported in British and American newspapers. These are sometimes contradictory, including differing accounts of the name used by the speaker and the wording of their message.