Robots

The Sleepers were five doomsday robots designed in Berlin by Nazi Germany as agents of destruction. After World War II, the Fourth Sleeper was entombed within a crypt that was sunk into the sea. The first three robots were activated by agents at a certain time in European villages, consisting of a giant human-like robot with blaster rays, a winged robot, and the 'brain', which resembled the Red Skull and was a powerful bomb. Despite Captain America and the personnel of a nearby U.S. Army base's attempts to stop them, the robots combined and flew towards the North Pole. While in pursuit with the military, Captain America surmises that the first Sleeper would use its blasts to dig into the ice, enabling the robot to travel into the Earth and explode, destroying the world, as the Red Skull had vowed that if he could not conquer the world, he would destroy it. To prevent this, Captain America is able to board the combined vehicle in midair and detonate the bomb early with a flamethrower, destroying the three Sleepers.^[1] The crypt containing the Fourth Sleeper was retrieved from the sea in modern times, and when the Sleeper reactivated it destroyed a seacoast smelting factory and battled Captain America. The Sleeper was ultimately rendered intangible by a "sonic crystal".^[2] Similarly, the Red Skull later activated the Fifth Sleeper, only to have it stopped by Captain America and the Falcon as well.^[3]

The Fourth Sleeper was later restored to tangibility by the Machinesmith and used as a "Trojan horse" to gain entrance onto Avengers Island to liberate the various robots incarcerated there. It was thwarted by Captain America, and badly damaged.^[4]

The damage done to the Fourth Sleeper was later repaired by the Machinesmith.^[5] The Fourth Sleeper was animated by the Machinesmith to join the Skeleton Crew in search of the missing Red Skull. It battled Hellfire Club mercenaries, and the Black Queen.^[6] Replicas of the five Sleeper robots were then pitted against Captain America and Diamondback.^[7]

Symbiote

When the Venom symbiote found out that it was pregnant again,^[8] it wanted to take care of its seventh spawn after being cleansed by the Klyntar.^[9] The Symbiote kept this a secret to Eddie Brock, until they were captured by the Symbiote Task Force, led by Claire Dixonbe working alongside the Scorpion, who wanted to rebond with the Venom symbiote.^[10] Luckily, Spider-Woman came and saved Eddie along with the symbiote from the Task Force. Then Eddie with Venom went to Alchemax to give birth to the new spawn. However, due to the experimentation it went through, the symbiote had a difficult pregnancy and meanwhile Mac Gargan arrived at their location and changed his plan to kill the Venom symbiote and bond to its more powerful spawn. Fortunately, Eddie knocked out both Mac and agent Claire Dixon. After giving birth to the spawn, Eddie and Venom entrusted Liz Allan to take care of the symbiote.^[11]

The spawn was then nurtured and raised by its parent who had been visiting at Alchemax to make it good in contrast to its other offsprings.^[12] However, after Venom was taken away by its original host, the Kree soldier Tel-Kar,^[13] the offspring bonded to Eddie and allied with the Warbride Skrull, M'Lanz, to save Venom and prevent Tel-Kar from using a deadly Skrull bioweapon.^[14] During the ensuing fight, Sleeper bonds to M'Lanz to save her, while Venom after being free from Tel-Kar's control rebonded to Eddie, leaving Tel-Kar to be exploded with the Skrull research base by the Kree military. Then Eddie with Venom and Sleeper returned to Earth as M'Lanz returned to space. However, Tel-Kar had survived the explosion and planned to use the bioweapon on the humans, but Sleeper intervened and bonded to Tel-Kar, lobotomizing him in the process and turning him into a body that Sleeper can pilot. After that, Sleeper bid Eddie farewell and with Tel-Kar's spaceship decided to go explore the universe.^[15]

Television

• The original Sleeper robot appears in the "Captain America" segment of The Marvel Super Heroes.
• A Sleeper robot appeared in the X-Men: The Animated Series episode "Old Soldiers".
• Robots of a similar design to the Sleepers appeared in the Spider-Man episode "Six Forgotten Warriors". They were created to protect the Red Skull's "doomsday weapon".
• Multiple Sleeper robots appear in The Avengers: Earth's Mightiest Heroes episode "Winter Soldier". A Sleeper attacks the Avengers' Hydro-Base to break out the Red Skull. While Captain America and Nick Fury are looking for the Winter Soldier, they find him fighting a Sleeper and help him defeat it. Afterward, the Winter Soldier tells them the Sleepers were activated after the Avengers foiled the Red Skull's campaign as Dell Rusk. Five Sleepers are activated in Washington D.C. and combine into one Mega-Sleeper to destroy it. However, the Avengers are able to distract it while Captain America and the Winter Soldier confront the Red Skull as he is piloting the robot. Their resulting fight damages the Mega-Sleeper, allowing the Avengers to destroy it.
• A variation of the Sleeper robots appears in the Avengers Assemble episode "The Sleeper Awakens", voiced by Liam O'Brien. This version is the Red Skull's A.I. system, referred to as Skull-Net, and battles the New Avengers.^[16]
• A variation of the Sleeper robots known as Sleeper-Mechs appear in season five of Agents of S.H.I.E.L.D., serving as shock troopers for HYDRA leader USAF General Hale. Introduced in the episode "All the Comforts of Home", they are remote-controlled by Hale's cybernetic associate Anton Ivanov. He and the Sleeper-Mechs continue to serve Hale until the episode, "The Honeymoon", when S.H.I.E.L.D. agent Elena "Yo-Yo" Rodriguez kills Ivanov, disabling the robots in the process.

Video games

• The Sleeper robot appears as the final boss in Captain America: Super Soldier. This version was discovered during the Middle Ages by Heller Zemo. Though they did not understand what the Sleeper was, Heller and his men realized it was something important and built Castle Zemo around its resting place. Hundreds of years later, during World War II, Heller's descendant Heinrich Zemo acquired the castle, believing he was destined to awaken the Sleeper and use it to help him in his plans for world conquest. However, he formed an alliance with HYDRA commander Johann Schmidt, who ousted Heinrich and occupied Castle Zemo so his top scientist Arnim Zola could study the Sleeper for HYDRA's purposes. In 1944, Captain America and the Invaders infiltrate Castle Zemo and successfully destroy the Sleeper after it was activated.