The Sleepwalkers were dream police. In that capacity, they apprehended any beings that invaded the sleeping minds of humans. Sleepwalker was tricked by his long time foe known as Cob Web (who like Sleepwalker had a real name that is unpronounceable by human language) into entering the mind of one individual (a New York college student named Rick Sheridan) and became trapped.
After a few confrontations in Rick's dreams, Rick reacted by tearing off Sleepwalker's Imaginator (a badge like device worn by sleepwalkers used to teleport around their home plane The Mindscape). This resulted in an odd situation further tying the two together. When Rick slept, Sleepwalker could materialize in reality or he could stay in Rick's mind and converse with him via his dreams. It was through a conversation in dreams that Sleepwalker was able to dispel Rick's initial fears that he was a malicious entity and work out agreeable terms to cohabitation.
Sleepwalker possessed a colorful gallery of mostly original villains, with a new one introduced each issue during the title's beginnings. Some of them could be considered corny even by the standards of their day. Some of them include the billiard-based 8-Ball, ultra nerdy Bookworm, prison escapees The Chain Gang and hypnotic songstress Lullaby.
Sleepwalker's first encounter with a super-villain was with 8-Ball. He spotted their unusual vehicle when he is scanning his new habitat from high in the sky. Sleepwalker arrived to question them if they are criminals, before reacting to their hostile actions. Still weak from floating in the sky, he gets taken down quickly. When asked, 8-Ball takes the time to politely explain his motives and why people commit crimes. Then he collapsed a building on Sleepwalker to finish him off. But his return to the ground restored Sleepwalker's strength and he rose from the rubble to send 8-Ball and his gang running. He held on to their vehicle, but Rick's awakening causes Sleepwalker to fade away, allowing them to escape.
After Thanos killed half of the universe, Sleepwalker aided Darkhawk, Deathlok, and Moon Knight to stop Eon's body from invading the universe. After the defeat of Thanos and Nebula, Sleepwalker still retained his memories about the events, but considered those memories just a dream.
Nightmare was considered one of the deadliest enemies of the Sleepwalkers, the dream police. He was unable to influence them due to them not needing to sleep. In a plan to change this he entered the mind of Sleepwalker's human host Rick. He used his mind to send Sleepwalker mad finally allowing him access to his peoples' minds. He sacrificed his way home to prevent the Nightmare from harming his people.
During the battle against the Magus, Sleepwalker battled various evil doppelgangers of the heroes, while also pretending to be his evil doppelganger. He also helped to defeat Magus' forces by channeling the mental powers of Professor X, Jean Grey, Psylocke and Moondragon.
During the rise of the Goddess Sleepwalker was among the individuals gathered by her to form an army to fight against all evil. While this was going on, he kept Rick asleep by drugging his orange juice. He, along with the brainwashed heroes battled the unaffected fellow heroes, until Adam Warlock exposed the Goddess' plans leading to the controlled heroes to turn on her. After their battle was undone by the Cosmic Egg and the destruction of Paradise Omega the heroes returned to their lives.
Invasion of the Mindspawn
When Cobweb formulated a plan to disrupt Sleepwalker's relationship with Rick, he disguised the Mindspawn as Sleepwalkers who started invading Earth with Sleepwalker being their supposed leader. Sleepwalker and the Avengers were able to thwart the invasion, however, with the Sleepwalkers' reputation ruined. He then pretended to destroy Rick's mind in order to protect him from the Mindspawn, but unfortunately the police had got hold of the Mindrake which was used to store Rick's mind. Sleepwalker tried to retrieve the Mindrake, however, the serial killer Jeremy Roscoe merged with one of Cobweb's demons and began spreading mass insanity, until Sleepwalker defeated him. Eventually, in the second battle against Cobweb Sleepwalker finally banished his archenemy, while seemingly sacrificing himself to save Rick.
Sleepwalker was among the people gathered by the Beyonder, in reality the cosmic being known as Stranger masquerading as the Beyonder. They managed to not kill each other thanks to Deathlok making a deal with the Beyonder who returned them to Earth.
A year or so later Sleepwalker came across Otto Octavius when he was inhabiting Peter Parker's body. Otto was infected with a Fear Worm that feeds on its victim's psyche and gestates in their empty bodies, but was able to destroy it with the help of the Superior Spider-Man.
- Superhuman Strength: Sleepwalker is powerful enough to lift and throws cars. His strength allows him to juggle cars with occupants with one arm. Like with his other abilities, it increases when he absorbs mental energies.
- Superhuman Durability: Sleepwalker is highly resistant to physical injury. He is capable of withstanding crushing force from a fallen building, grenade blasts, falls from great heights, and powerful energy blasts without sustaining injury. His resistance is such that he can take a punch from Hercules that sent him through the wall of a building and get up afterwards.
- Superhuman Reflexes: Sleepwalker's reflexes are such that he can catch a knife in his fingers and individually warp multiple bullets from an Uzi.
- Superhuman Stamina: Sleepwalker's body produces no fatigue toxins, granting him almost untiring physical stamina in all activities; his stamina is limited only by how much mental energy he contains. He doesn't need sleep and is immune to attacks that would render him, or takes effect when, unconscious. This proofs his race to the powers of even beings like Nightmare. In places that are filled with mental energy like the Mindscape, he has essentially unlimited stamina.
- Superhuman Vision: Sleepwalker possesses eyes that could see greater than human limits, spotting one unusual vehicle in the city from high in the atmosphere. He can see and track something as small and fast as supersonic bullets; can see and recognize various energies and can track them, including the energies from his own Warp Gaze; can even see otherwise invisible beings like astral projections and spirits. As he can analyze the structure of snow and manipulate air molecules, Sleepwalker may also be able see at the microscopic level.
- Warp Gaze: His only offensive power, with this vision-based power, Sleepwalker could alter the shape of physical objects and twist them to his purposes. Sleepwalker initially demonstrated this power by using it to distort a sidewalk to capture a criminal.
- His control is to the level where he can fashion an entire Spider-Man costume from raw fabric while having no knowledge of sewing. He has stated that in the Mindscape, his control is even finer and as sharp as a scalpel.
- With the exception of those that nullify his powers, the composition of the materials that he warps makes no difference in the ease that he can warp, freely manipulating both air and reinforced steel equally. He also used this ability once on air molecules to create a wind tunnel for faster aerial travel.
- While Sleepwalker can use the Warp Gaze directly on a living being, he has sworn an oath to avoid doing so because of the mental trauma it induces. Exceptions can be made in certain situations such as lethal threats, possession, and on extra-dimensional beings.
- When using the Warp Gaze on a possessed person, it acts to force out the possessing entity. It also reveals the true nature and banishes extra-dimensional beings like demons.
- Flight: Sleepwalker has a flotation-like flight that can let him travel fast enough to chase down a car. He can increase this speed by forming a wind tunnel with his warp gaze.
- Regenerative Healing Factor: Sleepwalker can heal from practically any injury by absorbing mental energy. He can absorb mental energy whenever he returns to his host or to the Mindscape. This allows him to recover from otherwise fatal injuries such as getting crushed by a wrecking ball and having his throat slashed open.
- Mental Power Amplifier: As a denizen of the Mindscape Sleepwalker can enhance mental powers from psionics and magic alike by his mere presence. During the Infinity War, Professor X, Jean Grey, Psylocke, and Moondragon were able to use him as a transmitter to affect the entire population of Earth and resist Magus' control. Doctor Strange's mental magic is similarly enhanced simply by having Sleepwalker nearby.
- Mental Energy Absorption: By absorbing the energy from mental attacks, he can increase his energy level. He may also absorb it from others' minds and with the use of a Mindrake.
- Expert Combatant: Sleepwalker has encountered a multitude of enemies with varying abilities both in Mindscape and Earth. This allows him to react immediately in a dangerous situation and is rarely surprised when encountering unusual enemies. When Rick suffers a temporary lapse in consciousness that made him fall out of a plane, Sleepwalker was able to assess the situation in a split-second and within mere moments, slowed Rick's descent and warped a windsock to catch him as he recovers consciousness. He has used power lines and electric appliances against his enemies. He is also very creative in the use of his Warp Gaze: creating disguises, forming aerial messages, repairing structures, and a tool for psychological warfare.
- Extra-Dimensional Knowledge: While he is ignorant to many regular Earth matters, he has shown extensive knowledge of the Mindscape and whatever traverses it. He knows information about beings like the demon Mr. Jyn, Nightmare, and even the mutant Portal who occasionally travels through the Mindscape.
- Mindscape Weapons Knowledge: Despite not carrying it, he has deep knowledge of weapons such as the Mindrake, intentionally using it on Rick Sheridan and knowing that it doesn't kill immediately.
- Language Assimilation: learned to speak English because that's the language his human host speaks. If Sleepwalker had been trapped in the mind of someone who spoke another language, like French or German, he would have begun using that language when he first appeared in the human world.
- Dependent Manifestation: Sleepwalker would automatically disappear from the material plane at whatever point Rick would awaken from sleep. This would often lead to his current heroic endeavor being aborted before he could accomplish his given task.
- Flight Ceiling: The further he floated from the ground, the weaker he would get. This was only shown in his second appearance and never mentioned again. He has even traveled to another planet with no ill effects. As he was surprised when he first discovers this, it can be presumed that this weakness doesn't exist when he is in the Mindscape.
- Light Addiction (developed later): An addiction to certain types of light from a synthetic diamond. This addiction became so overwhelming that Sleepwalker forced his way out of Rick's waking mind, putting the young man into a temporary coma.
- Imaginator device
- 82 appearance(s) of Sleepwalker (Earth-616)
- 9 appearance(s) in handbook(s) of Sleepwalker (Earth-616)
- 2 minor appearance(s) of Sleepwalker (Earth-616)
- 2 mention(s) of Sleepwalker (Earth-616)
- 2 mention(s) in handbook(s) of Sleepwalker (Earth-616)
- 64 image(s) of Sleepwalker (Earth-616)
- 5 quotation(s) by or about Sleepwalker (Earth-616)
- 1 item(s) used/owned by Sleepwalker (Earth-616)