
Isaiah Bradley is a fictional character appearing in American comic books published by Marvel Comics. The character is depicted as an early product of the United States' Super-Soldier program during World War II and an alternate version of Captain America.

James Buchanan "Bucky" Barnes is a fictional character appearing in American comic books published by Marvel Comics. Originally introduced as a sidekick to Captain America, the character was created by Joe Simon and Jack Kirby and first appeared in Captain America Comics #1 as the original and most well-known incarnation of "Bucky". The character is brought back from supposed death as the brainwashed assassin Winter Soldier, and later assumed the role of Captain America when Steve Rogers was presumed to be dead.

Captain America is a superhero appearing in American comic books published by Marvel Comics. Created by cartoonists Joe Simon and Jack Kirby, the character first appeared in Captain America Comics #1 from Timely Comics, a predecessor of Marvel Comics. Captain America was designed as a patriotic supersoldier who often fought the Axis powers of World War II and was Timely Comics' most popular character during the wartime period. The popularity of superheroes waned following the war, and the Captain America comic book was discontinued in 1950, with a short-lived revival in 1953. Since Marvel Comics revived the character in 1964, Captain America has remained in publication.

William Burnside, also known as the Captain America of the 1950s, is a fictional character appearing in American comic books published by Marvel Comics. He was created by writer Steve Englehart and artist Sal Buscema in Captain America #153–156 as an explanation for the reappearance of Captain America and Bucky in 1953 in Young Men comics and their subsequent adventures in the 1950s. It established through retroactive continuity that the character was a completely different one from the original Captain America, who was firmly established in The Avengers #4 as disappearing near the end of World War II.
Jeffrey Solomon "Jeff" Mace, also known as the Patriot and Captain America, is a fictional character, a superhero appearing in American comic books published by Marvel Comics. The character was created during the 1940s, a period fans and historians call the Golden Age of Comic Books. As the Patriot, he first appeared in Human Torch Comics #4, published by Marvel's 1940s precursor, Timely Comics.

The Red Skull is an alias used by several fictional characters appearing in American comic books published by Marvel Comics, primarily Johann Schmidt. The first Red Skull appeared in Captain America Comics #1, created by Joe Simon and Jack Kirby. Usually portrayed as a Nazi agent and protégé of Adolf Hitler who is disfigured or wearing a red skull mask, the Red Skull is regarded as the archenemy of the superhero Captain America.

Steven G. Rogers is a fictional character portrayed by Chris Evans in the Marvel Cinematic Universe (MCU) film franchise—based on the Marvel Comics character of the same name—commonly known by his alter ego, Captain America. In the films, Rogers is a World War II-era U.S. Army soldier who was given enhanced physical and mental capabilities with a supersoldier serum developed by the military and who was later frozen in ice for nearly seventy years. After being revived in the 21st century, Rogers becomes a key member and leader of the Avengers.

The Spirit of '76 is a fictional character appearing in American comic books published by Marvel Comics. Created by writer Roy Thomas and artist Frank Robbins as part of a World War II-era superhero team, the Crusaders, and patterned on the DC Comics group the Freedom Fighters, the character first appeared in The Invaders #14.

U.S. Agent is a fictional superhero appearing in American comic books published by Marvel Comics, usually those starring Captain America and the Avengers. He first appeared in Captain America #323 as Super-Patriot. He was later redesigned as a new incarnation of Captain America and, a few years later, as U.S. Agent.