Snake Men (Masters of the Universe) in the context of "Castle Grayskull"

Castle Grayskull is a fictional castle that forms a central location in the Masters of the Universe toy/comic/animation universe and also appears in the 1987 live action adaptation. The concept is credited to Donald F. Glut. The toy set was invented by Roger Sweet. Castle Grayskull was a "major feature of Mattel's line", and was "one of the most famous playsets of all time".

In the storyline of the franchise, it is the target of numerous attacks by Skeletor, Hordak and the Snake Men, all of whom believe that the secrets inside will allow them to conquer Eternia and the entire universe, and become the titular Masters of the Universe. Castle Grayskull plays a key role in the transformations of both He-Man and his twin sister She-Ra in the 1983–1985 He-Man and the Masters of the Universe series, and in its 1985–1987 spinoff/sister series She-Ra: Princess of Power.