Crash Bandicoot/Nightmare Fuel

You think that because these videogames have an excellent palette of colors doesn't mean it has something potentially creepy? Then you think wrong.

General

 * The Lab Assistants. It's revealed in Crash Bandicoot 3: Warped that they're all robots, but they look human by Crash standards in the first game. Their only means of attack (apart from standing there) in one level is to run at Crash with arms outstretched, occasionally generating electricity between their hands. It doesn't help that they return in Crash Bandicoot 2: Cortex Strikes Back, some assimilated into Borg-like space warriors, and the only way to beat them is to push them into a fire shield - and their standard cry is eerily cut off as they evaporate.
 * The Game Over screens of Cortex Strikes Back and Warped are somewhat creepy thanks to the vocal performance of Clancy Brown.
 * The first game's Game Over deserves mention too, as well as... well, the first game in general, as a whole. Despite the fact you can't save may be Fuel just to me in terms of gameplay (that is, an annoyance), the graphics weren't nearly as fine as they were in the second game. However, special mention goes to how, in the title screen, Crash screams in your face. And let's not even get started with Lights Out which is Exactly What It Says on the Tin... a bit too much if you screw up, alongside the music that accompanies it.

Crash: Mind Over Mutant

 * The Mount Grimly theme is extremely dark compared to the rest of the otherwise cheery and upbeat soundtrack.