Captain America's shield is his primary weapon. The most well-known of his shields is a disc-shaped object with a five-pointed star design in its center, within blue, red, and white concentric circles. This shield is composed of a unique combination of Vibranium, steel alloy and a unknown third catalyst, that has never been duplicated, called Proto-Adamantium. It is virtually indestructible. It is as much an offensive weapon as a defensive one for Captain America. Cap uses it against his enemies, mainly, by throwing it at them and can perform mindbogglingly impossible tricks with it.
He was attempting to perfect an indestructible alloy as strong as the legendary Adamantine, which Hercules' Golden Mace was made from. Dr. MacLain was hoping the alloy would provide a distinct advantage in the armor of American war machines, during World War II.
The doctor worked tirelessly, using a steel alloy (now known as Proto-Adamantium), and an unknown metal (now known to be Vibranium or more precisely Wakandan Vibranium). While the doctor was asleep, as a result of his exhaustion, an unknown factor caused the metals he was working with to bond.
The shield was cast by Dr. Myron. During his experiments, MacLain combined Vibranium with an iron alloy he was working with and created the disc-shaped shield. MacLain was never able to duplicate the process due to his inability to identify a still unknown factor that played a role in it. The shield was awarded to Captain America by the government several months after the beginning of his career.
The alloy was poured into the shape of a disc. Some sources say that Dr. MacLain chose the discus shape because of its versatility, while others say that he used an existing cast designed for tank hatches. Presumably, the titanium steel bolts used to fasten straps to the disc were also forged at this time. The U.S. government painted in its familiar red-white-and-blue pattern using titanium oxide paint (though it has been repainted since then). Later, the shield was presented to Captain America by President Franklin Delano Roosevelt.
Later, Dr. MacLain's attempts to duplicate the shield, minus Wakandan Vibranium and the mystery factor, resulted in True Adamantium. Because of this historical link, the unknown substance composing the shield is sometimes referred to as "Proto-Adamantium".
The shield was on Steve Rogers when he crashed in the arctic and was frozen in a state of suspended animation. After being revived by the Avengers, Tony Stark made several electronic and magnetic improvements upon the shield, which allowed Rogers to control the discus in flight. The additional components threw off the balance of the shield when thrown, however, and Rogers soon removed them.
In Cap's early adventures with the Avengers, the shield appeared to be destroyed a number of times, only to appear whole again in time for the next adventure. It was later explained that the curious Stark had frequently borrowed the unique shield for analysis and provided a steel replica for Cap to use each time. The true shield was once slightly dented by an enraged, Odin-Force-empowered Thor, using Mjolnir, but he later reconciled and pounded out the small dent.
During the original Secret Wars a portion of the shield was destroyed by Doctor Doom who had assumed the Beyonder's godlike powers. The Beyonder soon recovered his powers and, as a side effect, released a wave of energy that produced a "wish effect". That is, each person on Battleworld was able to harness a portion the Beyonder's infinite power to realize some wish. Cap's wish was to have his shield whole.
Later, Captain America lost his shield over the Atlantic Ocean and it sank to the bottom. Stark sent a crew to recover the shield, at considerable cost, and months later did manage to retrieve it (Cap used a series of steel replicas during this time). Unfortunately, the shield was dropped on the ship's deck during recovery and the once-indestructible shield shattered. After examining the pieces, Stark and Rogers discovered that its unique molecular structure had changed. A small sub-molecular imperfection, a single misaligned molecule, was introduced. With every blow the shield took, the Vibranium within absorbed more energy and the flaw propagated to other molecules until the shield's bonds were completely and spontaneously broken down. Worse still, the energies released by the Vibranium created a shockwave that spread like a "Vibranium Cancer", violently destroying any Vibranium it encountered. Eventually, the shockwave, feeding off each newly destroyed source of Vibranium, would reach the Great Vibranium Mount in Wakanda, resulting in a blast that could destroy the world. Rogers travelled to Wakanda with the pieces of the shield taped together, hoping he could save the world by using the remaining vibranium within the shield to absorb the shockwave. In doing so he was prepared to sacrifice what remained of the shield. However, the shockwave was first intercepted by the Klaw, who absorbed it into his own body of living sound energy. Klaw soon attacked Rogers with his augmented powers. When Cap reflexively raised his shattered shield in defense, the shards absorbed the energy and the ultra-powerful harmonics restored the Vibranium nanostructure.
For a time, Rogers was asked to relinquish the role of Captain America and the costume and shield were turned over to the new Captain America, John Walker. During this time, Rogers acted as "the Captain" and used a True Adamantium shield, provided by Stark. After the two had a falling out over the Armor Wars, Rogers decided to return the shield and, instead, used a pure Vibranium shield, provided by Black Panther. When Rogers re-assumed the mantle of Captain America, he reacquired the unique shield. As US Agent, Walker took on Rogers' Captain costume and Vibranium shield.
Thanos of Titan later shattered the shield with a single blow by using the power of the Infinity Gauntlet, but the shield was restored when Nebula obtained the Gauntlet and undid most of Thanos's villainy. On another occasion the shield was destroyed by the Molecule Man.
After the death of Rogers, Stark buried him with a replica, placed a replica in the Captain America Museum, and offered the original shield to newly revived Avenger, Hawkeye, but Hawkeye declined. After reading Rogers' will, which asked Stark to look-after Rogers' WWII partner Bucky, now calling himself the Winter Soldier, Stark offered the shield and title of Captain America to him. After Rogers' return from death, Barnes attempted to return it to him, but Rogers declined, after seeing a future event where Barnes died and believed that keeping the title of Captain America would save him.
Barnes carried the shield, until Sin, the daughter of Rogers' arch-enemy Red Skull, began calling herself the Red Skull and discovered an ancient Asgardian hammer, which made her the avatar of Skadi, daughter of the Asgardian God of Fear, Cul Borson. Wielding immense powers and an army of Nazis, Skadi destroyed the White House and Barnes was killed, attempting to stop her. Rogers took the shield and mantle of Captain America once again, but the shield was again destroyed, after Rogers threw it at the God of Fear himself and he broke it apart over his head, with his bare hands.
The shield was later reconstructed, by Stark using the mystical Asgardian metal Uru making it "stronger than ever." The weapon-smith Dwarves of Nidavellir that helped Stark were unable to remove a crack that went across the shield and Stark offered to take the scar off, but Rogers stated that it "gave the old girl a little bit of character."
The shield was stolen by an unknown super powered individual. Sam Wilson and Steve Rogers chased the thief but they escaped. 
Captain America's primary weapon is his shield, a concave disk 2.5 feet in diameter, 3 inches thick, weighing 12 pounds. The shield is made of a unique Wakandan vibranium and Proto-Adamantium alloy that has never been duplicated. Its atomic structure is possibly unique in the universe; Molecule Man stated that although Thor's hammer Mjolnir and the Silver Surfer's surfboard were bound together by strange forces, the shield was even stranger.
The shield has great aerodynamic properties: it is able to slice through the air with minimal wind resistance and deflection of path. Its great overall resilience, combined with its natural concentric stiffness, enables it to rebound from objects with minimal loss of angular momentum. It is, pretty much, virtually indestructible: it is resistant to penetration, temperature extremes, and the entire electromagnetic spectrum of radiation. The only way it can be damaged in any way is by tampering with its molecular bonding.
The shield is not only nearly indestructible, but it absorbs a great deal of kinetic energy from impacts because of its Vibranium component. That is why the Hulk and Thor can pound it while Cap is holding it, without simply sending him into the ground or the air. Cap has also used the shield to cushion the force of impact when dropped from several stories by standing on the shield.
The only vulnerable component that can be affected by conventional weapons are the shield's internal holding straps; the master blade wielding mercenary, Machete, managed to once in a trick-shot throw of his blades to sever them while Cap was wielding his shield. While this made the weapon much more cumbersome to use since it forced Cap to hold it by its rim, he was able to drive off the assailant so he could replace the straps at home. 
Other Shields Used by Captain America
- Originally Captain America carried a steel shield, resembling the traditional shield found in the Seal of the United States. This shield remained among the Captain's personal effects until it was crushed by Mr. Hyde in Avengers #275.
- A similar, traditionally-shaped shield made of vibranium was given as a gift from the Black Panther of Wakanda as a token of a pledge to stay out of World War II. Supposedly, it is on exhibit in a Wakandan museum.
- A third shield of the traditional design resided for some time in the Smithsonian museum. This version was used in combat against Hydra agents while the original was lost in the Atlantic. The "Smithsonian" variant was eventually destroyed in battle against the Kree.
- As "the Captain", Rogers used a disc-shaped shield composed of True Adamantium, given to him by Stark.Captain America #339
- After returning the adamantium shield following the Armor Wars, Rogers used a discus-shaped Wakandan vibranium shield given to him by the Black Panther.
- An Energy Shield from Sharon Carter, which was capable of changing shape due to a 'flexibility matrix.'
- A round Osmium Steel shield from Doctor Doom.
- A traditionally-shaped shield is currently being used by the Patriot. It is presumably a replica.
- A shield he used during the time Sam Wilson was wielding his round shield.
- An all black shield with four a white star in the middle. It was given to Sam by Misty Knight.
- Bucky Barnes' secondary shield had light blue stripes and a slightly darker middle.
Other Shield Wielders
- Sam Wilson, while he was standing in for Steve Rogers.
- Wonder Man while battling with the Avengers against Count Nefaria (after Cap was barely able to stand and pursue the Count and gave the shield to Simon).
- John Walker, while he was standing in for Steve Rogers.
- James "Bucky" Barnes, while he was standing in for Steve Rogers.
- Clint Barton, while he was temporarily standing in for Steve Rogers (when he was thought to be deceased).
- Kelsey Leigh, who was killed during a battle involving the Avengers and the Wrecking Crew trying to protect a downed Captain America.
- Bobbi Morse, who picked it up to defend the rest of the temporarily depowered New Avengers against the Wrecking Crew.
- Baron Zemo, who picked it up to defend Steve Rogers from a rampaging Moonstone, when the Avengers and Thunderbolts came to blows.
Alternate Realities' Shield Wielders
- Major Victory, the leader of the Guardians of the Galaxy, found the shield in that alternate future.
- Nathan Dayspring, the leader of the Clan Rebellion, found the shield in that alternate future.
- Crusader, alternate reality daughter of Steve Rogers and Rogue, where the Secret Wars participants never left Battleworld. She wielded Mjolnir in conjunction with it.
- Superman used the shield, along with Mjolnir, to fight alongside the Avengers and his fellow Justice League teammates.
Alternate Reality Versions
|In Earth-138, Captain Anarchy's shield had a unique symbol with a thin black strip replacing the big internal red stripe.||Spider-Verse #2|
|In Earth-398, Cap is altered by Morgan Le Fay's reality distortion wave, his shield seems to reflect the medieval-like setting.||Avengers (Vol. 3) #2|
|In Earth-691, in the 31st century, Major Victory acted on rumor and legend to find the shield, which he used as a symbol to rally the warring people of Earth after they were freed from the conquering Badoon.|||
|In Earth-717, Cap's shield is in fact the Shield of We-Pi-Ahk which, when thrown, transformed into a manifestation of the Eagle Chief.||What If? (Vol. 4) #1|
|In Earth-1519, Cap hails from a reality where the Aztecs had never been conquered, his shield seems to reflect this.||Marvel Zombies 3 #4|
|In Earth-1610, Captain America used a triangular shield in action during World War II. When he was revived Rogers implemented a shield made of an unknown metal. The shield was given to him by S.H.I.E.L.D.. This shield was later destroyed by Valkyrie and her Golden Blade. Thor replaced it with one forged by elves. This shield was also destroyed by Gregory Stark. Since that time, it appears Captain America has used a circular shield.||Ultimates #1|
|In Earth-2189, Cap's shield is chipped from conflict with Namora, because he stood in the way of her plans.||Exiles #47|
|In Earth-3931, Cap The Vampire King's shield has no blue in it whatsoever.||Exiles #31|
|In Earth-4162, Cap is a little more commando, and his shield seems to reflect that.||Exiles #52|
|In Earth-4400, Cap was killed attempting to prevent Hyperion from taking over his planet. His shield is cracked.||Exiles #44|
|In Earth-4935, Nathan Dayspring and Tetherbood led a squad of the Clan Rebellion to obtain the shield, which Nathan used to inspire liberty and justice in his followers and bore into many battles, until it was ripped from his arm.|||
|In Earth-5113, Cap's shield is corrupted by Dormammu, with jagged spikes around the shield's rim, giving it an appearance similar to a buzzsaw.||Defenders (Vol. 3) #4|
|In Earth-5692, Cap is the Game's reigning gladiatorial champion and the Skrulls love him. His shield seems to reflect Skrull technology in appearance.||Exiles #9|
|In Earth-8311, Captain Americat's shield was heavily chipped and scratched in a battle with Kang the Conqueror.||Marvel Tails Starring Peter Porker the Spectacular Spider-Ham #1|
|In Earth-8910, Captain America's shield had spikes protruding on the rim.||Excalibur #14|
|In Earth-9047, Chaplain America wielded a shield with a similar look and function to its Earth-616 counterpart.||What The--?! #1|
|In Earth-9200, Rick Jones gathered the shield and other artifacts into a memorial of the heroes slain by the Maestro. After the Hulk defeated the Maestro, Jones' ashes were epoxied onto the shield and the Hulk threw it into space as an eternal memorial.||Hulk: Future Imperfect #1|
|In Earth-9602, Super-Soldier's shield was that of the Superman Symbol.||Marvel Versus DC #3|
|In Earth-9907, Captain America was murdered by Red Skull, who proceeded to steal his shield. It was eventually recovered by the Captain America of Earth-982. He gave the shield to American Dream, who took it back to Earth-982.||A-Next #10|
|In Earth-10011, Cap is corrupted by the unseen "many-angled ones", and his shield seems to reflect that.||Realm of Kings #1|
|In Earth-11124, Captain America's shield served the headpiece of his tombstone.||Fear Itself: Fearsome Four #4|
|In Earth-11326, Cap's shield is blue and black instead of red and blue. The blue also appears to be an energy shield, while the black part has a much bigger star and can be stored on Cap's back like Cap's usual way.||Age of X: Universe #1|
|In Earth-12041, King T'Chaka gifted Howard Stark with Vibranium alloy in gratitude for his and Captain America's help defending Wakanda from a Hydra invasion in World War II. Howard crafted the Vibranium into Captain America's iconic shield, which was later frozen with the captain himself in the Arctic. Years later, after both were thawed out by S.H.I.E.L.D., T'Chaka's son T'Challa forcefully took the shield back from Rogers as property of Wakanda, partially due to the belief that his father was too trusting to give Vibranium to outsiders and partially to use it as bait to draw out a thief who had been stealing from Wakanda's mines. After spending some time fighting with the Avengers, T'Challa finally considered Rogers worthy of wielding the Vibranium shield and allowed him to reclaim it.||Marvel's Avengers Assemble|
|In Earth-13153, Captain America's shield had pieces missing and was heavily scarred. It was wielded by Captain Last until his death at the hands of Spider-Man.||Miles Morales: The End #1|
|In Earth-13584, Captain America's shield was obtained by Ant-Man after the former's death. Pym gave the shield to a reality-displaced U.S. Agent, repainted in Walker's color scheme.||Dark Avengers #188|
|In Earth-14137, Captain America's shield lacks the white stripe.||All-New, All-Different Avengers Annual #1|
|In Earth-14831, Captain America's shield was damaged in a battle with Ultron, with several punctures and pieces chipped off. Ultron then gave the shield to his robotic Captain America.||Avengers (Vol. 5) #31|
|In Earth-15329, Captain America's shield was stored in Maestro's trophy room.||Spider-Man 2099 (Vol. 2) #10|
|In Earth-15513, Cap was a gladiator, and his shield seems to reflect this.||Planet Hulk #1|
|In Earth-21050, Cap's shield is black instead of blue.||Marvel Apes: Prime Eight Special #1|
|In Earth-21923, would later be recovered by The Avenger and given to the new Captain America.||Avengers of the Wastelands #2|
|In Earth-32323, Cap's shield was pure black with the white star.||Civil War (Vol. 2) #1|
|In Earth-37072, Cap is effected by Kulan Gath's Master Spell, his shield seems to reflect the Dark Ages-like setting.||Exiles #56|
|In Earth-42777, a world visited by Weapon X, Captain America was killed in the Mutant Wars, instigated by Magneto. His shield was shown to have been melted through.||Exiles #23|
|In Earth-61112, Cap's shield was destroyed in battle with Ultron Sentinels.||Avengers (Vol. 4) #12.1|
|In Earth-64087, Cap is evil, and his shield seems to reflect that.||Avengers #7|
|In Earth-93070, Cap's shield is light blue rather than red.||What If...? #51|
|In Earth-96433, Cap lives in a medieval world, and his shield seems to reflect that.||Dark Reign: Fantastic Four #2|
|In Earth-807128, Cap's shield was taken from him after his defeat a the hands of the Red Skull and placed in his trophy room. Years later, Logan used the shield to decapitate Shmidt..||Wolverine (Vol. 3) #72|
|In Earth-199999, it's a circular disk about 762 mm (30") in diameter, weighing 12 pounds, and was made of a Vibranium, the rarest metal on Earth at the time. The amount of Vibranium used for Cap's shield is all the Vibranium that the United States had access to. The shield was made by Howard Stark. Black Panther scratched shield with the claws on his Panther Habit, but it was repaired by Tony Stark. The shield is three times lighter than steel and negates large amounts of damage by absorbing vibrations. The shield had great aerodynamic properties: it was able to slice through the air with minimal wind resistance and deflection of path. Its great overall resilience, combined with its natural concentric stiffness, enabled it to rebound from objects with minimal loss of angular momentum. It was virtually indestructible: it was resistant to penetration, and extreme temperature. The shield was badly damaged during a battle with the Thanos of an alternate timeline. After Steve Rogers retired to a parallel timeline where he grew old, he returned to the main timeline with a new intact shield that he passed on to Sam Wilson. Feeling unfit to take on Steve's mantle, Sam turned it back to the government, who appointed John Walker as the new Captain America and gave him the shield. John served as Captain America until he publicly decapitated a Flag Smasher named Nico, forcing Sam to take back the shield.||Captain America: The First Avenger|
|In Earth-600043, the shield has no white in it, with that part being instead transparent. The shield can withstand shotgun bullets, and Cap throws it using the boomerang effect; however, when returning, the shield drops to his feet and he does not catch it. He puts the shield in front of the handlebars of his motorbike.||Captain America (1979 film)|
|In Earth-10631, the shield was combined with Eye of Agamotto and known as the Eye of Amerigotto, it was covered in mystical symbols and was magical in nature.||Captain America: Who Won't Wield the Shield #1|
|In Earth-TRN524, Cap's shield has no star and the blue is black.||Dark Avengers|
|In Earth-TRN562, the second shield was primary crafted with Vibranium given to the United States of America by King T'Chaka of Wakanda. During a battle with Hydra, Captain America and his shield would be separated and time-displaced. The shield would be discovered by Falcon and given to Steve when he joined Avengers Academy. A variation of the original, triangle shield was created by the Wasp and given to Steve alongside a variation of his original uniform as a ninety-six birthday present.||Marvel Avengers Academy|
|In Earth-TRN721, Cap lives in the Land of Oz, and his shield seems to reflect that.||Dark Reign: Fantastic Four #2|
|In Earth-TRN861, Captain America is from the Old West, and his shield seems to reflect that.||LEGO Marvel Super Heroes 2|
|In Earth-TRN876, the shield had the Union Jack rather than a star. The outer bar was also blue rather than blue. After being transported to the future, the inner bar was painted blue and the symbol turned grey.||What If...? (animated series) S1E01|
|The reality this razor-pointed shield came from is unknown, it was found impaled in Maverick.||Exiles #62|
|In an Unknown Reality, Captain America's shield replaced the star with the Deadpool symbol and the white stripe was instead colored black.||Deadpool Kills the Marvel Universe #4|
|In an Unknown Reality, Captain Gwen-Merica's shield doubled as the body of her guitar.||Gwen Stacy #1|
|In an Unknown Reality, Captain America's shield was chipped during a battle with Mephisto and his forces.||Amazing Spider-Man (Vol. 5) #74|
- Originally, Marvel decided to discontinue use of Captain America's traditionally-shaped shield after rival comic book publisher MLJ (now Archie Comics) complained that the design was too similar to that of their own patriotic hero, "the Shield." It was at that point that they first switched to the discus-shaped shield. No explanation was given at the time.
- Rogers' indestructible shield has often been referred to as being an adamantium-vibranium alloy. This is a result of early entries from the Official Handbook of the Marvel Universe Vol. 1: Captain America's entry in Official Handbook of the Marvel Universe #2, Captain America's Shield, and Adamantium, in #15.
- The Adamantium entry mentions that the adamantium (a steel alloy) used in the shield was an adamantium compound, known as Proto-Adamantium.
- Captain America #303 mentions only the steel alloy, the adamantium being a latter finding while searching to recreate the shield's alloy.
- The shield featured in the Marvel Cinematic Universe is described as made of Vibranium only. This is due to Adamantium being included in FOX's film rights at the time Captain America: The First Avenger was produced. It is unknown what, if any, changes to this will occur following the Disney-FOX merger.
- In the 1960's and 70's, writers of Captain America and the Avengers pondered the true nature of Cap's indestructible shield. Some credit on the canon for the shield must be given to letter writer Fred Janssen. In the letters page of Captain America #145, he details a theory that the shield is based upon Vibranium, Adamantium, and the work of Myron MacClain. Although other ideas proposed by Janssen are not upheld, the genesis of this letter provided Marvel creators a basis for defining Cap's Shield.
- On the late night television show The Colbert Report, Stephen Colbert had Captain America's shield hanging on the wall of the set. It is now featured on the set of his show The Late Show with Stephen Colbert.
- Captain America's shield can't be controlled by Magneto's powers.
- During promos for the Marvel's Agents of S.H.I.E.L.D. "Uprising" event, Captain America's shield briefly replaces the S.H.I.E.L.D. logo--specifically the faded version of the shield used in promotional images for Captain America: The Winter Soldier.
- 4474 appearance(s) of Captain America's Shield
- 625 minor appearance(s) of Captain America's Shield
- 38 mentions of Captain America's Shield
- 4858 image(s) of Captain America's Shield
Links and References
- Captain America's Shield at Wikipedia