The Pit of Shadows is the name of a location that features in He-Man and the Masters of the Universe.
This dark region is situated on the planet Eternia and was beneath the mountain citadel of Darksmoke, which serves as the home of Dragonkind. It is the home of a mystical flame that is needed to empower the ancient dragon known as Granamyr. The journey to the Pit of Shadows is shown by fiery signs to guide travelers, but it is noted as being a dangerous as well as perilous journey. This is because the underground caverns are populated by Ice Spiders and a pair of fire-breathing Gryphons that prevent pilgrims from entering into the Pit of Shadows unless they are judged to be good, wise, and brave. Upon passing these guardians, travelers enter into the Pit itself, which is covered with magical fire and it requires magic in order to take a piece of the flames with them to the surface. After leaving, pilgrims have the danger of getting lost within the caverns.
In later years, the dragon Morning Star secretly put out the magical flames of Granamyr with an Ice Crystal, thus weakening the ancient dragon king. This allowed Morning Star to incite a war against Humans by claiming that mankind was responsible for the vile deed. When He-Man and Man-At-Arms arrived, Granamyr explained that without his magic he would be unable to stop the war from escalating out of control. It was then that Orko proposed that he would use his magic to bring a portion of the mystical flame from the Pit of Shadows to re-empower Granamyr. After battling an Ice Spider and passing the guardians of the Pit, they succeeded in their task whereupon He-Man broke through a section of the cavern in order to make his own way to the surface without getting lost in the underground chambers.