"When Captain America throws his mighty shield / All those who chose to oppose his shield must yield / If he's led to a fight and a duel is due / Then the red and the white and the blue'll come through / When Captain America throws his mighty shield."

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There aren't many super weapons with their own theme song, but there aren't many as iconic as Captain America's shield. The round shield first appeared in "Captain America Comics" #2. It is made of a mysterious alloy with properties of vibranium and adamantium and is indestructible, except when it isn't. The shield has been a constant companion of Steve Rogers and has lasted from World War II into the far future, and has been wielded by several other men and women, mostly with honor and good intentions (although sometimes not). Here are 15 superheroes who wielded the shield.

15 STEVE ROGERS

The first shield-bearer, of course, is Steve Rogers, the 98-pound weakling with a stellar strength of character even before his physique was altered to reach the maximum of human capability. Debuting in "Captain America Comics" #1, he was a leader in the effort to fight World War II even before the United States joined the Allies. Since then, he's been a mainstay of the Avengers, frequently battled alongside Nick Fury and S.H.I.E.L.D. and has been at the forefront of major events throughout the Marvel Universe's history.

Captain America has constantly been regarded as an exemplar of justice and freedom, until it was revealed in "Captain America: Steve Rogers" #1 that he is secretly loyal to Hydra, and has been since his childhood and throughout his career. This is a Steve Rogers who has been altered by the Cosmic Cube and has had false memories implanted, and the ramifications from those changes are still playing out.

14 ISAIAH BRADLEY

Before Steve Rogers took up the shield, there was another brave soul who did: Isaiah Bradley, a Tuskeegee Airman. Bradley was one of 300 African American soldiers secretly experimented on by the U.S. Army in Project: Rebirth, the government's early attempts to create the Super-Soldier Serum. This was revealed in "Truth: Red, White & Black," the 2003 miniseries written by the late Robert Morales and drawn by Kyle Baker.

Bradley is one of only seven survivors of the trials, but is the last one standing when he undertakes a mission behind enemy lines in Germany to destroy that nation's efforts to create its own super-soldiers. To do so, he disguises himself with a spare Captain America costume and shield. After completing the mission, however, Bradley is charged with stealing the costume, court-martialed and imprisoned for nearly 20 years, until he is pardoned by President Eisenhower. Sadly, the unrefined version of the serum in Bradley's system caused debilitating effects on his mind and body.

13 THE SPIRIT OF '76 / THE PATRIOT

After several years during which Captain America was not featured in any comics, he was reintroduced to the Marvel Universe in 1964's "Avengers" #4. However, the explanation for his absence (that he had been in suspended animation since 1945) didn't account for comics that featured Captain America into the 1950s. "What If?" #4, "What If The Invaders Stayed Together After World War Two?," partially retconned away that discrepancy. It revealed that after Captain America and Bucky went missing in 1945, the U.S. government covered up the incident and recruited replacements.

William Naslund, The Spirit of '76, accepted the request, along with Fred Davis as the replacement Bucky. As Captain America, Naslund served through the end of World War II, sometimes with the All-Winners Squad. However, he was killed in action in 1946 while the All-Winners thwarted an attempt to kidnap a congressional candidate in Boston: future President John F. Kennedy. Right after The Spirit of '76 was killed, costumed hero the Patriot, Jeff Mace, found his body and pledged to serve in his stead. Mace served as Captain America until 1950.

12 GRAND DIRECTOR

William Burnside had a stalker-ish level of fascination with Captain America and with Steve Rogers, gaining a Ph.D. on the topic, even visiting Germany and uncovering documents with the original Super-Soldier formula. At the outset of the Korean War, Burnside made a deal with the F.B.I. to reveal the formula to them if he could be the new Captain America. However, by the time his preparations were complete (including multiple surgeries for Burnside to resemble and sound like Steve Rogers, as well as adopting his name) the war ended and the program was shelved.

When a Communist spy posed as the Red Skull and attacked the United Nations, Burnside and partner Jack Monroe acted on their own as Captain America and Bucky to stop it. After that, they carried on as Captain America and Bucky, fighting Communists, but slipped into madness because their transformation was incomplete without exposure to the stabilizing Vita-Rays. They were put into cyrogenic suspension for their own safety, but released a quarter-century later and battled the original Captain. Burnside later became the Grand Director, leader of the neofascist National Force.

11 ROSCOE SIMONS

Steve Rogers had a crisis of conscience when he battled the Secret Empire, in "Captain America" #169-176. Following the threads of a plot to discredit him takes Captain America all the way to the White House, where he thwarts a coup d'etat led by a hooded man described only as a high-ranking government official. "Number One," strongly implied to be President Nixon, commits suicide, and an unnerved Rogers renounces the Captain America identity.

Three well-meaning do-gooders step up to take the Captain America mantle only to find out the hard way that it's not as easy as it looks. Pro baseball player Bob Russo, on his first time out, swings into a wall and breaks his arm, while a biker named "Scar" Turpin takes on six thugs and gets the snot beaten out of him. Finally, gym owner Roscoe Simons, who refuses to be dissuaded by The Falcon, shows his mettle in a fight. He gets Steve Rogers' blessing and a bit of mentoring and training by The Falcon. Unfortunately, in stopping a bank robbery, Simons and The Falcon are captured by minions of the Red Skull. Insulted at finding a substitute in the costume, Red Skull beats Simons to death.

10 AMERICAN DREAM

"What If" #105 gave us a look at a possible future for the Marvel Universe, showing us Peter Parker's daughter, May, becoming the costumed hero Spider-Girl, and meeting that era's Avengers. This led to the character getting her own title, "Spider-Girl," the flagship of the MC2 line of comics. Spinoff title "A-Next" introduced Shannon Carter, cousin of Sharon Carter and a tour guide at the Avengers Museum. Carter resolves to join the Avengers, taking on the name American Dream. She trained extensively to overcome damage from a car crash and devised her own costume and weapons, throwing discs that looked like mini-shields. She got her wish to join the Avengers in "A-Next" #4.

In an adventure that took the team to an alternate reality where the world was conquered by Dr. Doom, American Dream met the original Captain America, who was leading the resistance. With the new team's help, the regime was overthrown and Captain America gave American Dream the shield of that world's defeated Cap. American Dream also appeared in a five-issue limited-series and in the four-issue "Captain America Corps" series.

9 CYCLOPS (ULTIMATES)

The crossover adventure in "Ultimate X-Men/Fantastic Four Annual" #1 and "Ultimate Fantastic Four/X-Men Annual" #1 presents an alternate future for the Ultimate Universe. Here, Mr. Fantastic succeeds in finding a way to cure The Thing, but his device also strips the powers from Cyclops and Jean Grey, while Captain America ages and dies. To continue the fight on behalf of mutants, Scott Summers takes the shield and adopts the mantle of Captain America, although he redesigns the shield in X-Men livery.

Cyclops gathers an X-Men team consisting of Rogue, Shadowcat, Wolverine and a new male Phoenix to go 20 years into the past to kill Reed Richards and the Fantastic Four, so as to prevent the dystopian future that spins out of the "Ultimatum" crossover. However, things quickly go wrong when Wolverine reveals he is a Sentinel in disguise. The Wolverine Sentinel attacks and kills most of the team, including Cyclops.

8 DAVID RICKFORD

David Rickford had a short career as a Captain America, appearing only in "Captain America" #615.1." At that time, Bucky Barnes had been in the role, but was sabotaged by Baron Zemo, who made public his past as Soviet assassin the Winter Soldier. This resulted in Barnes' incarceration in a Russian gulag.

To entice Steve Rogers to again take up the Captain America guise, Nick Fury, posing as the Power Broker, arranged for a new group of volunteers to test what they were told was a reconstituted Super-Soldier serum. Among them was decorated Special Forces soldier Rickford, who instead was put through the Power Broker augmented strength process. After some training, Rickford went public as Captain America, but after a successful first day, he was captured by minions of A.I.M. who planned to convert him into a M.O.D.O.K.. Steve Rogers rescued him and demanded Rickford resign the Captain America role, lest he get himself killed.

7 SUPER-SOLDIER

1996's  "DC vs. Marvel" crossover series also introduced a series of spinoff titles published by both companies. Under the banner "Amalgam Comics," these books featured characters, locales and concepts that were a blend of elements from both companies.

Super-Soldier was a mix of Captain America and Superman. "Super-Soldier" #1 gave us his origin: He was Clark Kent, a 4-F volunteer who was injected by a "Super-Soldier" serum blended with cell samples from a body found in alien rocket that crashed on Earth in 1938, and also was blasted with solar radiation. The combination gave Kent powers and abilities far beyond those of ordinary mortals. He had super-strength, stamina, flight, invulnerability, heat vision and super-hearing. As Super-Soldier, he carried a shield that bore Superman's "S." But in battle with Ultra-Metallo, Super-Soldier crashed into the Altlanic Ocean, and is frozen in ice and lost for decades. He has a second adventure with Sgt. Rock and His Howling Commandos in "Super-Soldier: Men of War" #1, taking down Major Zemo, a mix of DC's Iron Major and Marvel's Baron Zemo.

6 DANIELLE CAGE

In today's Marvel Universe, Danielle Cage is a baby, the daughter of Avengers Luke Cage and Jessica Jones; her birth occurred in "The Pulse" #13. She is destined for greatness, however, because when she grows up, she'll be Captain America!

Cage's grown-up self appears in "Avengers: Ultron Forever" #1, brashly taking down agents of the Golden Skull. She has inherited the strength of her mother and the toughness of her father, and uses a shield tricked out with devices that allow her to fire it off and have it return. Danielle is whisked away through time by Doctor Doom to join other Avengers from different periods: Jim Rhodes as Iron Man, Thor Odinson, Thor's successor, an early Hulk, the Vision and the Black Widow. The team was assembled to defeat Ultron, who had conquered the world in a timeline 50 years in the future. Cage is currently on the roster of "U.S. Avengers."

5 MAJOR VICTORY

A founding member of the original Guardians of the Galaxy, young Vance Astro adored space. He volunteered for an interstellar mission to Alpha Centauri that required him to spend much of the thousand-year journey in stasis. A special containment suit was provided for infrequent periods of wakefulness, and he developed psionic powers. Unfortunately, Earth developed faster-than-light propulsion during the time he was gone, beating him to Alpha Centauri by some 200 years.

While with the Guardians in the 31st century, Major Victory searched for the lost shield of Captain America. In the effort, he battled Interface, who also sought the shield for its power. With his powers, Interface removed Major Victory's containment suit, causing him to age, and took the shield but discarded it because it seemingly had no power. When Major Victory seized it, the shield gave him strength and inspiration, which are the true powers of the shield. He continued to carry it, using his psionic powers to steer it when thrown.

4 U.S. AGENT

When he was recruited to fill the role, John Walker intended to honor Captain America and the ideals he represents, but found it increasingly difficult to do because he holds a different worldview than Steve Rogers does. Walker first appeared in "Captain America" #323 as Super-Patriot, an opponent of Captain America's idealistic perspective. Walker had undergone the Power Broker's strength augmentation and was working with a promoter to pay for it.

Later, Rogers is summoned before the Commission on Superhuman Activities, which declared everything related to Captain America is property of the federal government and instructed him to work solely on its orders. Rogers refused and resigned, and the Commission approached Walker about wearing the costume. Walker, as the new Captain America, proved to be more violent and impulsive, even killing some of his opponents. Rogers, now known as The Captain, battled Walker in fight instigated by the Red Skull. In the aftermath, Walker was fired and persuaded Rogers to re-take the Captain America mantle. Walker then became U.S. Agent, in a costume similar to Rogers' costume as The Captain.

3 BUCKY BARNES

From the beginning, there was James Buchanan "Bucky" Barnes, Captain America's partner and friend, working side-by-side with him in adventures through World War II. Until that fateful moment, revealed in "Avengers" #4, in which a drone plane explosion in 1945 caused Captain America to be lost at sea and killed Bucky. Or so everyone thought, anyway.

In 2005, Captain America encountered a new antagonist, a KGB assassin known as the Winter Soldier. Bucky had been found by Soviet forces, outfitted with a prosthetic arm and brainwashed. The Soviets then sent him on covert assassinations, placing him in cryonic suspension afterward for months and years at a time. Captain America, with unwavering faith that Bucky could be saved, used the Cosmic Cube to free him from his programming. However, Captain America was seemingly killed while surrendering at the end of "Civil War." His last request, delivered to Tony Stark, then head of S.H.I.E.L.D., was for Bucky to carry on in his stead.

2 SAM WILSON

As the Falcon, Sam Wilson is one of Captain America's longest-serving partners and is the first African-American superhero in Marvel Comics, following the Black Panther's 1966 debut by three years. He was introduced in "Captain America" #117 in 1969 as a man with an affinity for birds and soon becomes a costumed hero, although his past as a street hustler has been retconned away. He gained an upgraded costume that allows him to fly in "Captain America" #170.

After Steve Rogers loses the Super-Soldier serum in his system, becoming as physically frail as an average 90-year-old, he directly asks Wilson to take over as Captain America. As the All-New Captain America, Wilson has had a rocky tenure; he is not universally accepted in the role, alienates a large part of the public when he reveals his politics, and is being undermined by Steve Rogers, whom he does not know is a mind-controlled Hydra operative.

1 SUPERMAN

It takes an extremely dire circumstance for the No. 1 hero of another universe to wield the seminal weapons of the Marvel Universe. It happened in 2003's "JLA/Avengers" #4, the culmination of the long-delayed inter-company crossover between Marvel and DC, chock full of wonderful moments.

In the story, both teams are working at the behest of cosmic entities (the Marvel Universe's Grandmaster and the DC Universe's Krona) to recover totems of power, six from each of the universes. But the Grandmaster, whose champions are the Justice League, is working a hidden agenda to protect his universe from Krona, who in turn is willing to destroy all the known universes in his increasingly reckless quest for knowledge of the truth of creation. The Avengers and the JLA unite for an assault on Krona and his forces that is a cover for Superman to attempt to strike him down. To ensure he can, Captain America gives Superman his shield. Thor gives Superman his hammer, to boot.

Who was your favorite shield-bearer? Be sure to let us know in the comments!