The Cybernauts first appeared on episode "The Cybernauts: In which Steed receives a deadly gift-and Emma pockets it."

Designed by Dr. Armstrong (Michael Gough), a mad scientist in a wheelchair, the Cybernauts were programmed to follow the signal from a special radio-transmitter pen planted on the bodies of electronics industry executives and then kill them with a deadly karate chop.

These killer robots were finally deactivated when undercover agents John Steed (Patrick Macnee) and Mrs. Emma Peel (Diana Rigg) orchestrated the death of the mad doctor.

John Steed and Emma Peel examine a Cybernaut

The Cybernauts were resurrected in the episode "Return of the Cybernauts: In which Steed pulls some strings-and Emma becomes a puppet."

This time around, Dr. Paul Beresford (Peter Cushing), the brother of Dr. Armstrong devised a plan to kill both Steed and Mrs. Peel by capturing scientists to assist him in his deadly plot.

Reluctantly, one of the scientists designed a watch which turned the wearer into a puppet to be controlled by Dr. Beresford. Emma Peel donned one of these watches and consequently attempted to kill Steed. Steed, however, managed to place one of these watches onto a Cybernaut which ran amok and killed Beresford.

Dr. Paul Beresford with assistant

The Cybernauts appeared for a third time in the episode entitled "The Last Of The Cybernauts...?" on THE NEW AVENGERS/ITV/1976-77.

In this final encounter, we find Frank Goff (Robert Gillespie) a former assistant of Dr. Armstrong (released from prison after ten years) abducted and forced at gunpoint to reactivate the Cybernauts for Felix Kane (Robert Lang), a double agent horribly scarred and crippled in an accident with a petrol tanker...an accident caused by the members of the Avengers team Mike Gambit (Gareth Hunt) and Purdey (Joanna Lumley).

When his first attempt at killing the Avengers failed, Kane programmed a second Cybernaut to kidnap a leading cybernetics expert, Professor Mason (Basil Hopkins) to incorporate a series of cybernetic limbs with his brain waves...turning Kane into a half-man, half-machine.

Filled with revenge, Kane's cybernautic body traveled to Purdey's home to mutilate her body. John Steed and Mike Gambit came to her rescue by spraying Kane's cybernetic limbs with plastic skin which deactivated the electrical impulses and rendered Kane immobile.

TRIVIA NOTE: On the original AVENGERS episode “Never, Say Never Again” Mrs. Peel is watching her television at the beginning of the show. It showed scenes from “The Cybernauts.”

This episode was about the Ministry of Technologies Neoteric Research Unit that housed humanoid robots created by Professor Frank N. Stone (Christopher Lee). They were virtually indestructible and planned to trade places with political figures and other notables. They were defeated when they were exposed to their Achilles heel - 540 megacycles short wave band frequency.

After subduing the robots Mrs. Peel said “We’ve just averted a disaster. Can you imagine plastic politicians. Her partner Steed responded “Who would ever know the difference.”