Origin

In a world where strange creatures live that borders on the minds of all intelligent life, there is a force of beings that protect the sleeping minds of humans. For if they were not protected, dangerous beings would enter the minds of sleeping humans. One of the beings that protects the human minds, what humans call 'Sleepwalker', was tricked by his enemy, Cobweb, into entering the mind of Rick Sheridan. After confronting Sleepwalker in many of his dreams, Rick tore off Sleepwalker's Imaginator. This caused Sleepwalker and Rick to bond together. Now, whenever Rick Sheridan goes to sleep, Sleepwalker materializes into reality. Rick and Sleepwalker have agreed that when Sleepwalker comes out, he fights crime.

History

Sleepwalker has fought a wide array of villains, from the billiard based 8-Ball, to Crimewave, to the Chain Gang. In the Infinity War, Sleepwalker helped channel the minds of Professor X, Jean Grey, Moondragon, and Psylocke. During the battle against the evil doppelgangers that Magus made, Sleepwalker fought some of the evil clones and saved some citizens. Sleepwalker also impersonated his own doppelganger. During the Infinity Crusade, he was captured by Goddess and brought to the 'Counter-Earth'.

Cobweb wanted to finally defeat Sleepwalker so he devised a plan. Cobweb would disguise his minions as Sleepwalker's race and make everyone believe that Sleepwalker was their leader. Then, everybody would hate Sleepwalker. The plan went into action. Sleepwalker and the Avengers stopped the invasion, but the public still believed that Sleepwalker was the leader of a race that was going to try to take over. Cobweb attacked again but Sleepwalker defeated him for good, banishing him. Sleepwalker seemingly died afterwards. It was soon revealed that Sleepwalker did not die, he was only trapped inside Rick Sheridan's mind.

Alternate Realities

Earth-6215

On Earth-6215 Sleepwalker has been separated from Rick Sheridan, and is a member of the League of Losers. He takes control of peoples dreams and uses them to alter reality.

Earth-1610

In the Ultimate Universe, Sleepwalker are creatures that police the "mindscape" dimension, where the Shadow King originated.