Deployable Cover

So, you and your squad are off on a mission. You've got armour, guns, grenades, etc. - everything you need. But there's a catch - on this mission, there is likely to be little cover. What do you do? Take some of your own with you, of course!

Deployable Cover can be anything from an energy barrier that deflects bullets to a big pavise that can be planted into the ground to protect you from arrow volleys. Often, the deployable cover won't be as durable as natural cover, eventually getting destroyed after it is shot enough (though, in the case of an energy shield, it may reactivate after a short time). It will, however, last indefinitely if it is left alone.

If you carry the cover with you whilst making use of it, then it's closer to a shield.

Anime and Manga

 * Planet Defensors in Mobile Suit Gundam Wing can be deployed to form a Deflector Shield.

Tabletop Games

 * Champions supplement Gadgets! The Force Wall Generator was a device which, when placed on the ground and activated, would create an energy shield to block incoming fire.
 * GURPS: Ultra-Tech has various portable force screen generators while High-Tech provides explosives blankets which SWAT officers can use backward to protect themselves from attack.
 * In Games Workshop's The Lord of the Rings Strategy Game, Corsair Arbalesters carry around big wooden pavises.
 * The Warhammer Fantasy Siege Rules allow archer units to carry pavises.
 * Dungeons & Dragons has rules that allow a tower shield to be planted, meaning the user sacrifices all actions and the shield's usual bonus to AC and takes full cover (untargetable, although enemies can certainly aim for the shield) instead.

Video Games

 * Players carrying riot shields in various shooter games become this for their teammates.
 * This piece of equipment in Halo 3 is the Trope Namer. You just tossed it out and it would throw up a shield that you could shoot through while blocking your enemies' shots.
 * It also had the Bubble Shield, a form of deployable cover that created a sphere of protection 4m in diameter to wherever it was tossed. It could be walked through, but anything thrown or fired at it was unable to penetrate, even your own shots. Halo Reach included it as an armor ability, also making it smaller.
 * Global Agenda features this in standard and Limit Break formats for the Robotics class.
 * The Block ability in S4 League.
 * The Geth in Mass Effect seem to be fond of deploying hexagonal energy shields in areas with little cover.
 * The Collectors in Mass Effect 2 also deploy shields, circular but still with a glowing hexagonal pattern in them.
 * Similarly,
 * In Borderlands, the Soldier's turret features an energy shield, as well as shooting things.
 * Girders in Worms can be deployed absolutely anywhere on the map and sort of magically spring into existence, and can be used for a certain degree of cover wherever it is needed.
 * In at least the third Ratchet and Clank game you can buy deployable cover.
 * GI units in Command & Conquer Red Alert 2 can deploy sandbags which gives them increased resistance and also allows them to use their machine guns, but makes them immobile. The Guardian GI in the expansion can do the same, but using metal plates instead which makes them impervious from getting roadkilled by vehicles. How they get sandbags and metal plates is anybody's guess, and worse, how they set them up in less than a second. GDI riflemen in C&C 3 can build foxholes, which are basically Garrisonable Structures though this cost some cash and takes a while to build, and if you leave them empty, the enemy can use them too.
 * The Locusts in Gears of War have bombs that make pillars of earth shoot up from the ground, which they then use as cover.
 * Gears of War 2 introduces a shield that can be made into this.
 * Gears of War 3 will have Silverbacks, mech suits that can turn their legs into cover at the cost of not being able to move while they do it.
 * Eldar guardians in Dawn of War 2 may deploy energy shields.
 * Unreal featured a forcefield item that could be activated to seal off a doorway or provide cover in a gunfight.
 * Fracture's gameplay was built around the Entrencher, a device which in theory could raise and lower the ground to create cover and foxholes as needed. It didn't work well enough to make up for otherwise bland gameplay and story writing.
 * Zerg Defiler can cast a spell that creates a cover, rendering all direct ranged attacks useless against units under it, including your own.
 * StarCraft II ups the ante with sentries, the premiere defensive units of the Protoss. Their standard defense, the force field can be used to prevent melee units from getting up close and to keep ranged units out of attack range when you pair them up with Colossi. Their secondary defense the guardian shield reduces incoming damage to great effect since it does so over a wide area.
 * Engineers in Stronghold are capable to create cheap and expandable shields that can be deployed in the battlefield to protect other units from enemy fire.
 * The Auger's secondary fire in the Resistance series places a short-lived, man-sized wall of energy in front of the user, which is impervious to everything except Auger shots.

Webcomics

 * Schlock Mercenary has "[//www.schlockmercenary.com/2017-11-14 fragsuits]" — heavy Power Armour, which breaks into a pile of barricade components and flying mini-drones, that have their own power sources and low-grade AI. As such, it's obviously rather niche, skill-intensive and expensive equipment. And since it's doffed in combat situations, must be worn over common low-profile power armour (which itself comes with flight/Inertial Dampening gravitics, Collapsible Helmet and basic lifesupport).

Western Animation

 * The Herculoids.
 * Episode "The Time Creatures". The title opponents could press a button on their helmets and create a force field barrier in front of them.
 * Episode "Invasion of the Electroid Men''. The title creatures could create an energy wall as a movable barrier.
 * Space Ghost episode "The Looters". Brak's ray shelter can generate an Impregnashield (a rectangular force field) in front of it.

Real Life

 * The Pavise was a shield designed to protect archers and crossbowmen from incoming projectiles, they often had a spike in the bottom, allowing it to be put in place, thus protecting the owner without them having to hold it.
 * The Mantlet was a movable barrier that would protect from arrows, that could be put into position by the soldiers using it.
 * Shell holes are often used as cover. In a variation of this trope, troops have at rare times requested artillery fire just to create them.
 * More commonly, such as in the latter part of World War 1, armies would employ a "creeping barrage" tactic, where the artillery would continually lay down fire just ahead of the advancing troops, using the shell blasts themselves as a form of cover.
 * the veined octopus sometimes carries coconut halves around to use as portable armor. When it sees a predator it reassembles the coconut halves into a ball with itself protected inside.
 * When dismounted, troops can use friendly vehicles, such as Infantry Fighting Vehicles and tanks as cover during gunfights. This way they can have some protection from the small arms fire that likely makes up the majority of any fight, and are better able to pick off anyone carrying an anti-tank weapon. If you ever choose to use this technique, remember that the vast majority of motor vehicles are not actually bulletproof.
 * Of course, this started back in the horse era with defensive circles of carts or vans, since even very light fortifications are far better than no fortifications, more so in the open and against cavalry (and cavalry was the most likely force superior numbers of which you won't see coming in time to get away).
 * Be wary of being near vehicles with reactive armor, as it explodes into clouds of sharp, hot, toxic shards when struck by some forms of anti-vehicle weaponry.
 * There are actually foldable kevlar-sheets that can be carried around like a suitcase (it intentionally resembles one) and quickly folded out to give some level of protection agains pistol caliber weapons. They fit here since they aren´t that mobile and the user has to manually hold them up with one hand while returning fire with the other.