In "The Television Companion" (1998), David J. Howe and Stephen James Walker wrote that "Terror of the Zygons" gave a stereotypical portrayal of the Scottish and showed how much the show had changed since abandoning its regular UNIT premise. They felt that the story gave UNIT its "dignity and believability" and praised the conception of the Zygons, though they noted that the shape-shifting concept was not original. Despite classifying the Skarasen as the "major weakness", they said "the story remains a strong one". In 2010, Mark Braxton of "Radio Times" praised the "exquisitely horrible" design of the Zygons and the cliffhanger of the first episode where a Zygon attacks Sarah. He also was positive towards guest actor John Woodnutt and the incidental music, calling the whole production "a class act", aside from the Loch Ness Monster. DVD Talk's John Sinnott gave the story four and a half out of five stars, praising the cast and the design of the Zygons.