Superhuman Restraint Unit

The (Anti- )Superhuman Restraint Unit is a fictional special operations unit of S.H.I.E.L.D. appearing in American comic books published by Marvel Comics, designed by penciller, Howard Chaykin. These S.H.I.E.L.D. agents wear armor, and use hardware, designed by Tony Stark and Stark Enterprise employee, Kenny and are trained to take down superhuman combatants. During the events of the Civil War, where these agents were sent to bring in rogue superheroes, its members (and the armored suits themselves) became known as Cape-Killers (sometimes written Capekiller ).

History
The first appearance of an armored superhuman restraint unit in the Marvel Universe was in the pages of Marvel UK's The Mighty World Of Marvel, during the events of the Jaspers' Warp story arc. In this tale, insane reality warper, Jim Jaspers became the Prime Minister of the United Kingdom and turned the UK into a fascist state. As PM, he enforced "Super Hero Legislation"; using armored agents of S.T.R.I.K.E., the UK division of S.H.I.E.L.D., to hunt down and detain superhumans within the UK. These anti-superhuman agents were called "Beetle" squadrons, due to their beetle head shaped helmets, and were best known for gunning down Tom Lennox, Betsy Braddock's lover.

During the events of Marvel Comics' Civil War crossover, the United States government passed a Superhuman Registration Act and used a division of S.H.I.E.L.D. agents, recently trained to deal specifically with superhuman threats, to enforce the law. These foot soldiers of S.H.I.E.L.D., known as (Anti-)Superhuman Restraint Unit, and more commonly Cape-Killers, were spread out across Marvel comics, and came into conflict with various superpowered individuals throughout the event and into the subsequent Initiative story arc. Following the Secret Invasion storyline, Norman Osborn is placed in control of S.H.I.E.L.D.'s replacement, H.A.M.M.E.R., and discontinues Stark's line of Cape-Killer technology.

Cape-Killer armor
Not much has been revealed in the comics about the Stark Enterprise's armor which is used by the Cape-Killers. During appearances of this unit, two different styles of helmet have been used; a Riotsquad style helmet and, more commonly, a helmet with a Filter style gas mask.
 * Armor

These suits are out-fitted with internal comm systems, and hover discs that give the wearers the ability of flight which have been seen in various comics.

The Cape-Killer's various firearms in early comics shot tranquilizer darts though later they have been shown to use genetic paralyzer laser weapons.
 * Weapons

The armor suits have been shown to be susceptible to power surges in several issues, and Nick Fury, S.H.I.E.L.D.'s former director who went into hiding after the events of the Secret War limited series, would later develop a device that transmitted an electromagnetic overload pulse-broadcast straight into their comm systems, shutting down their suits and frying their electrical systems that was shown to take down several unit members at once.
 * Weaknesses

It was later shown that former Stark Enterprise employee and a designer of the Cape-Killer armor, Kenny has an override code on his high tech palm pilot that can freeze the suits.

Known Cape-Killer teams and members

 * 9-6 - unlicensed hero recovery team.
 * Agent Abrams - he led a Superhuman Restraint Unit to capture Robert "Nitro" Hunter; they failed and died when they were caught in a Nitro generated explosion.
 * Agent Cleery
 * Agent Doug ???, and another Cape-Killer - Security for the Santa Monica Farmers' Market.
 * Aerial Company C & Aerial Company E - Posted in the Manhattan area follow the events of World War Hulk.
 * Dum Dum Dugan
 * Force Unit 9 - Avengers/Stark Tower Guards.
 * Team Cobra - which included Commander Gabriel Jones, and Agent Whitman
 * Team 1 & Team 2 - assigned to the Baxter Building.
 * Special Agent Marquez, and her partner Agent McAllister

Video games
They appear in Marvel Ultimate Alliance 2; as enemies if the player chooses the Anti-Registration side of the story, if the player chooses the Pro-Registration side they appear as allies.