A hero published by Marvel Comics. Sleepwalker first appeared in Sleepwalker #1 in 1991.

Bordering on the edge of human consciousness is another dimension called the Mindscape. It is the world of dreams and half-shaped imaginings. Within this dimension, a group of beings exist who act as guardians against the chaos of the realm. They are known as the Sleepwalkers. They are green skinned beings with glowing red eyes and a large bulbous head.

The Sleepwalkers protect the Mindscape using their Warp Vision. When the beams from the Sleepwalker's eyes strikes any inanimate substance, the Sleepwalker is able to animate the object, bending it and reshaping it to their will. They use this ability to reshape the stuff of the Mindscape to protect the innocent.

The hero Sleepwalker was linked to a teen named Rick Sheridan, when Sheridan grabbed an amulet from the Sleepwalker in a dream. After that when Sheridan would sleep, the Sleepwalker would appear in our reality. At first, he struck fear into those around them, but eventually the other-dimensional warrior began to fight the evil around him, defending this plane of reality as well as his own.

The Sleepwalker encountered such villains as the Bookworm, another high school student who could bring the characters in books to life by force of his will. Bookworm chose villainy rather than doing what any normal teenage boy with that power would do, which is lock himself in the bathroom with a stack of dad's old Playboys and never been seen from again. Another villain against which the Sleepwalker fought was 8-ball, a criminal mastermind who committed crimes with a giant eight ball helmet on his head and a rocket powered cue as his weapon.

Sleepwalker is possibly the worst conceived and executed hero in all of Marvel's long history, bar none. He is possibly the Marvel Comics' editoral staff's attempt to hook into the very popular Sandman series that was being published at DC Comics at the same time. You can imagine the story meeting going something like this:

Editior:I have called this meeting to discuss this new Neil Gaiman series over at DC, Sandman. It is getting positive reviews and high sales. Do we have anything to tap into this market of the sleep-based superhero?
Assistant Editor:Well, there is Nightmare...
Editor:Is he a hero?
Assitant Editor:No. A villain.
Editor:Can we make him a hero?
Assitant Editor:Not really.
Editor:Okay, then we need a brand new hero. One who has to do with sleep. Right?
Assistant Editor:Right!
Junior Writer:Right!
Editor:And he will be done the Marvel Way!
Unison:The Marvel Way!
Editor:Okay, ideas?
Writer:Well, there is this teenage boy who has a girlfriend and a single mom, and he has conflicts with them...
Assistant Editor:Can we call him Rick?
Writer:Sure. Rick's the typical teenage boy's name. And it has worked before.
Junior Writer:Oh, and when he falls asleep, he becomes a super-hero and fights crime!

The result of this meeting (or one probably eerily similar) was Sleepwalker. The fact that the hero's adventures are effectively based on the fact that when danger rears its ugly head his alter-ego has to fall asleep would seem to be a major flaw in the concept of the hero. This along with the villains that they pitted him against made the comic's short run longer than it should have been.