You may have known the 1970s Cylons in Battlestar Galactica were originally supposed to be reptilian creatures in cybernetic suits, but did you realize how many looks they went through? Check out some concept art by Ralph McQuarrie and others.
The Galactica fansite Galactica.TV has a great feature on the evolution of the Cylons in the 1970s series, including some art I haven't seen before from Ralph McQuarrie, the concept artist who also worked on the original Star Wars films. And some amazing production photos. (Way more art at the link.) The Cylons were originally supposed to be reptilian aliens, but the studio put the kibosh on that idea because the idea of showing actual living creatures being killed was deemed too nasty for prime time. Hence the robotic Cylons instead.
Ralph McQuarrie's original concept art of the reptilian Cylons
Ralph McQuarrie's original concept art of the reptilian-looking Cylons
A drawing created by Jean-Pierre Dorleac after the fact, illustrating how his original version of the Cylons might have looked.
The Cylons' Imperious Leader, as designed by Andy Probert
Ralph McQuarrie's painting of Baltar and two Cylon centurions.
An early Cylon centurion helmet design based on Ralph McQuarrie's design
A mannequin wearing part of the Cylon centurion costume.