Nightmare King

Villain and main antagonist of Little Nemo: Adventures in Slumberland

Little Nemo comics
No existence has been recorded in the comics.

Little Nemo: Adventures in Slumberland (movie)
Main villain and antagonist in the movie, the Nightmare King is considered ruler of all nightmares and Nightmare Land. Though sometimes referred to as simply "The Nightmare" through the film, he is the ruler, nonetheless. Trapped behind the forbidden door, for most likely centuries, he is accidentally released by Little Nemo, when Nemo is made curious by Flip (who had no idea what was behind the door either) to open the forbidden door to see what's behind it. Nemo had opened the door with a key given to him by the King that could open any door in Slumberland.

Once free, the Nightmare King kidnaps King Morpheus and brings him to Nightmare Castle. Nemo and his friends make a daring rescue in which the Nightmare King is vanquished by the royal scepter and peace is once again brought to Slumberland.

The Nightmare King is voiced by Bill Martin.