This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Rainbow Brite
In the movie, Rainbow Brite and Krys, young children, are chased by monsters that want to eat them.
The Dark Princess and the lengths she'll go to to get what she wants can be pretty scary. When the source of her power is finally destroyed, she tries to ram into Spectra with her spaceship in the hopes of destroying it and any hope of the universe's recovery.
The movie opens with her being told that stealing Spectra could destroy the universe. She doesn't care.
One episode of the show has Murky capturing and torturing Moonglo with bright lights. In the same episode, he nearly kills Rainbow Brite by pushing her into a pit.
When she returns in the series, the Dark Princess plans to turn Rainbow Brite into a diamond and wear her around her neck.