4. The Ice Warriors In "Cold War"
Part of the sinister appeal of the Ice Warriors in their initial appearance in the Troughton Era, along with their imposing armor and hissing speech, was that the viewer never got to see exactly what was contained within those iconic helmets, the mystery adding a level of dread to their fearsome appearance. "Cold War" however ruined that forever with the ill-advised CGI reveal that they look like, well, a ropey CGI lizard. The idea and setting (80's Russian Nuclear Sub) for this episode are unique, but once we see underneath Skaldak's helmet this is just ruined for me. This same basic concept (single monster that usually travels in packs, versus the Doctor and pals in a small, enclosed space) was executed much better in the Eccleston episode "Dalek", where the lone Dalek actually conveys a sense of menace. We can only hope the helmets stay on if Moffet decides to bring the Ice Warriors back for Series Eight.