Grayskull is a fictional castle in the Masters of the Universe franchise, known for its iconic design and significance in the storyline. It serves as the home of He-Man, the main character, and is a source of great power. The castle is often depicted as a mysterious and ancient structure, with a skull-like facade and a magical aura. The castle is also the location of the Sword of Power, which grants He-Man his incredible strength and abilities. Within its walls, various secrets and artifacts are hidden, making it a central hub for battles between good and evil forces in the series.