Nemo was originally the protagonist of the comic strip Little Nemo in Slumberland. The full-page weekly strip depicted Nemo having fantastic dreams that were interrupted by his awakening in the final panel. The strip is considered McCay's masterpiece for its experiments with the form of the comics page, its use of color, its timing and pacing, the size and shape of its panels, perspective, architectural and other detail.
Little Nemo in Slumberland ran in the New York Herald from October 15, 1905, until July 23, 1911; the strip was renamed In the Land of Wonderful Dreams when McCay brought it to William Randolph Hearst's New York American, where it ran from September 3, 1911 until July 26, 1914. When McCay returned to the Herald in 1924, he revived the strip, and it ran under its original title from Aug 3, 1924, until December 26, 1926, when McCay returned to Hearst.
A weekly fantasy adventure, Little Nemo in Slumberland featured the young Nemo ("No one" in Latin) who dreamed himself into wondrous predicaments from which he awoke in bed in the last panel. The first episode[a] begins with a command from King Morpheus of Slumberland to a minion to collect Nemo. Nemo was to be the playmate of Slumberland's Princess, but it took months of adventures before Nemo finally arrived; a green, cigar-chewing clown named Flip was determined to disturb Nemo's sleep with a top hat emblazoned with the words "Wake Up". Nemo and Flip eventually become companions, and are joined by an African Imp whom Flip finds in the Candy Islands. The group travels far and wide, from shanty towns to Mars, to Jack Frost's palace, to the bizarre architecture and distorted funhouse-mirror illusions of Befuddle Hall.
The strip shows McCay's understanding of dream psychology, particularly of dream fears—falling, drowning, impalement. This dream world has its own moral code, perhaps difficult to understand. Breaking it has terrible consequences, as when Nemo ignores instructions not to touch Queen Crystalette, who inhabits a cave of glass. Overcome with his infatuation, he causes her and her followers to shatter, and awakens with "the groans of the dying guardsmen still ringing in his ears".[b]
Although the strip began October 15, 1905 with Morpheus, ruler of Slumberland, making his first attempt to bring Little Nemo to his realm, Nemo did not get into Slumberland until March 4, 1906 and, due to Flip's interfering, did not get to see the Princess until July 8. His dream quest is always interrupted by either him falling out of bed, or his parents forcibly waking him up.
On July 12, 1908, McCay made a major change of direction: Flip visits Nemo and tells him that he has had his uncle destroy Slumberland. (Slumberland had been dissolved before, into day, but this time it appeared to be permanent.) After this, Nemo's dreams take place in his home town, though Flip—and a curious-looking boy named the Professor—accompany him. These adventures range from the down-to-earth to Rarebit-fiend type fantasy; one very commonplace dream had the Professor pelting people with snowballs. The famous "walking bed" story was in this period. Slumberland continued to make sporadic appearances until it returned for good on December 26, 1909.
Story-arcs included Befuddle Hall, a voyage to Mars (with a well-realized Martian civilization), and a trip around the world (including a tour of New York City).