This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / New Super Mario Bros. U
The opening of the game is pretty jarring, with the giant Bowser claw crushing the heroes and throwing them out of the kingdom.
In a certain set of haunted levels in the Soda Jungle, you can see a giant, painted, Mega Bowser in the background. He has no eyes and just sits there looking like he wants to eat you. Wait did his eyes move?