10. The Cybermen In "Revenge Of The Cybermen"
The Cybermen as presented in classic episodes like "Tomb of the Cybermen"and "Earthshock" are sinister automatons, emotionless and ruthless. However, the intimidation factor of the Cybermen in this story is somewhat hindered by what becomes glaringly obvious to even the most inattentive viewer, and it's possibly the worst Achilles Heel in the history of design. The Doctor off-handedly mentions their huge weakness: contact with gold will destroy them, and then mentions that Planet Voga is wait for it mostly composed of gold. It's not hard to add up these two facts and deduce how the Cybermen are going to be killed this time. And why, oh why, are the Cybermen trying to attack a planet made of gold anyway? It's like Superman voluntarily wearing a Kryptonite suit. It doesn't make a lick of sense, like most of this forgettable disaster of a story. Why would a race so technologically advanced as the Cybermen possess such a glaring design flaw of having their chest unit, their most vulnerable spot, totally unprotected on their body? This also happens to be how the 5th Doctor defeats the Cyberleader in "Earthshock". At least the Sontara''s weak spot on the back of the neck, so is slightly harder to reach in combat.