Cyberman by Adrian Salmon.

It was always the Cybermen that scared me the most.
I grew up with Jon Pertwee's Dr. Who but still remember a few episodes of Patrick Troughton's character. I bought Tomb Of The Cybermen on DVD a few years ago and was stunned that I actually remembered some of the scenes. They stuck in my mind all these years, waiting to claw their way out, much like the Cybermen did in the third episode.
Epic.
Scary.


Adrian Salmon Convention sketch from 2005

I came across an artist called Adrian Salmon who was already drawing a Cyberman for another Dr. Who fan, albeit a younger fan than me but some years. I asked for a sketch of one of the earliest versions of the monster and Adrian was more than happy to produce this whilst discussing all things Who.
OK, purists might want to argue that Cybermen are more Cyborg than Robot, and I would agree that you have a point but for me Cybermen stray into the robot mold as they aren't, typically, left with any human emotion or intelligence. They've been re-programmed.