Terror of the Zygons


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Terror of the Zygons

Serial Code


First Transmitted

30 August 1975

Final Ratings






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Regular Cast

Tom Baker (Doctor Who), Elisabeth Sladen (Sarah Jane Smith), Ian Marter (Harry Sullivan)

Guest Cast

John Woodnutt (Duke of Forgill), Nicholas Courtney (Brigadier Lethbridge-Stewart), John Levene (RSM Benton), Lillias Walker (Sister Lamont), Robert Russell (The Caber), Angus Lennie (Angus) [1, 3], Tony Sibbald (Huckle) [1-2], Hugh Martin (Munro) [1], Bruce Wightman (Radio Operator) [1], Keith Ashley, Ronald Gough (Zygons) [2-4], Bernard G. High (Corporal) [2], Peter Symonds (Soldier) [3].


Written by Robert Banks Stewart
Directed by Douglas Camfield
Produced by Philip Hinchcliffe


When The Doctor, Sarah and Harry arrive in Scotland, having received an urgent request for assistance from the Brigadier, they discover that the mysterious force which has destroyed three oil rigs has left giant teeth marks on the wreckage.

The mystery deepens leading them to the shores of Loch Ness where they find that the legendary monster really does exist – and it’s the murderous tool of the Zygons, aliens intent on overpowering the planet.

The Doctor and his companions must find a way to defeat The deadly Loch Ness Monster and its controllers, but the Zygons have the terrifying power to change shape and the Doctor is in grave danger when he finds that his friends and allies are not always what they seem…


  • The Zygons made an earlier attempt to take over the Earth, as revealed in The Bodysnatchers.
  • Although this marks Harry’s last official story as a companion, he returns in The Android Invasion, System Shock and Millennium Shock.
  • This story had working titles of: Loch Ness, The Secret of the Loch, Secret of Loch Ness, The Loch Ness Monster and The Zygons.
  • This story was originally planned to end Season 12, but was pushed back to the start of Season 13 in order to allow the series to shift its broadcast schedule from a January start (as had been the case since 1970) to September Although debate has arisen regarding a later delayed-broadcast story, The Next Doctor, regarding what season it belongs to, no such debate appears to exist regarding Terror of the Zygons which, despite its production schedule, is universally considered part of Season 13.
  • Radio Times credits John Woodnutt as Duke of Forgill for Part One, Broton for Parts Two and Three, and Broton/Duke of Forgill for Part Four. All on-screen credits read Duke of Forgill.
  • This marks the only time one companion who had already been with The Doctor before another one joins remains with him after the second companion leaves, with the exception of Katarina and Sara Kingdom, who weren’t there very long, and ended up dying. Generally, The Doctor’s roster of companions revolves fairly consistently.
  • Final regular appearance of the Brigadier
  • The Zygons return in The Day of the Doctor
  • Order the DVD
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