DC Comics has thousands of characters in their stable, but their "Big Three" have been around since the Golden Age of Comics in the 1940s. Many believe they constitute the quintessential superheroes. None stand taller than Superman, created by Jerry Siegel and Joe Shuster in 1938. He first appeared in Action Comics #1, a "strange visitor from the planet Krypton," raised by a Kansas farmer and devoting his superhuman strength and powers to the good of all mankind.
DC's second great character, Batman, occupied a much darker side of the superhero spectrum. He debuted in Detective Comics #27 in 1939, created by Bob Kane and Bill Finger. The son of wealthy parents who were murdered by a street criminal when he was just a child, Bruce Wayne trains his mind and body to perfection, then dons the menacing costume of a bat in order to frighten evildoers; he's noted for being one of the only superheroes with no special powers.
The final member of the trio is Wonder Woman, created by William Moulten Marston and first appearing in All-Star Comics #8 in 1941. As one of the first female superheroes---an Amazonian princess who fought the Nazis on behalf of the United States---she became a feminist icon and role model for little girls everywhere.
Marvel Comics rose to prominence during the Silver Age of Comics in the mid-1960s. Their characters stood apart from DCs by being more morally complex, and possessing more human flaws. Their banner figure, Spider-Man, was a bullied teenager who gained arachnid-like abilities when bitten by a radioactive spider. He first appeared in Amazing Fantasy #15, courtesy of creators Stan Lee and Steve Ditko, and unlike other superheroes, his abilities didn't cure mundane problems like meeting girls or paying his bills. Other Marvel characters followed a similar path, including the X-Men--- centered around a group of heroes born with their powers and hated by the very people they wish to protect---and the Incredible Hulk, a misunderstood monster triggered by bouts of extreme rage.
The mid-1980s saw the appearance of new comic book characters who stretched the notion of what comics could be. Art Spiegelman recounted the Holocaust using anthropomorphic animals in his underground comic "Maus," featuring Jews as mice and Nazis as cats. Author Alan Moore and artist Dave Gibbons completely upended the superhero mythos with their book "Watchmen," which posited flawed characters like Rorschach and Night Owl struggling to interact with a very real world. Neil Gaiman took comics into the realm of dark fairy tales with the Sandman, a living embodiment of dreams joined by metaphorical figures such as Death and Destiny.