What if Thor was racist? That question you never asked was answered by Stormfront, who made his first appearance in The Boys #31 by Garth Ennis and Carlos Ezquerra. In public, Stormfront was a reincarnated Viking who led the superhero team Payback, a group made up of heroes who couldn't get into the Seven. Stormfront had electrical powers and weather control so everyone believed his cover story.
In reality, Stormfront was a former Hitler Youth in World War II who became a super-soldier created by the Nazis, which made him, by virtue of his association if not his nature, extremely racist. The fact that he shared the name of a racist neo-Nazi website wasn't a coincidence. He kept up the charade for years until he was beaten to death by the CIA hit squad, The Boys.
After the terrorist attacks on the World Trade Center in 2001, legendary writer and artist Frank Miller announced plans to create in his words "propaganda" against Islamic terrorists in the form of a graphic novel starring Batman called Holy Terror. Eventually, because DC rejected the idea, Miller removed Batman and replaced him with another superhero of his own creation, the Fixer.
The Fixer launched his own war against Islamic terrorists in the fictional Empire City, slaughtering with equal parts brutality and racism. At one point, the Fixer sneered that a captured terrorist's name was probably Mohammed, and the Fixer and his partner attacked worshippers of Islam and terrorists as if they were both the same. The world of Holy Terror supports his racism, though, because it portrays a world where all Muslims are evil.
In 1990, the miniseries Bratpack explored the dark side of being a superhero's sidekick with the story of four teenagers adopted by a group of psychotic antiheroes. In the miniseries, the teens quickly discovered their heroes were driven more by commercialism than by justice, and were corrupted by their mentors' desires.
One teenager became the new Kid Vicious, led by Judge Jury. Judge Jury was a straight-up Nazi who encouraged his ward to take steroids, tortured him by making Kid Vicious crawl through broken glass, and killed suspects. More than justice, he preached racism. He criticized Kid Vicious for taking him to a store run by Jewish owners, wore a Klu Klux Klan-style hood and targeted minorities over white criminals. He was a brutal satire of the fascist superhero.
In 1988, V For Vendetta (Alan Moore, David Lloyd) imagined a revolutionary named V fighting against a modern-day fascist government in Britain. After a nuclear holocaust, the Norsefire government took control and massacred all "undesirables," including minorities. The government used a number of tactics to control the people, including near-constant surveillance and propaganda. One of the government's most popular forms of propaganda was Storm Saxon, a superhero TV show steeped in racism.
In the world of Storm Saxon, African-Americans are oppressing the Caucasian race, constantly in search of white property to destroy and white women to rape. Storm fights exclusively minorities in the name of the white race, calling them "black cannibal filth." He's openly racist in a world of racism, which fits him perfectly. Thankfully, V shut him down along with the rest of Norsefire.
In 1937, two Chicago ad execs Bob Stark and C.L. Nutt created the Golden Age superhero, Hoverboy. During World War II, Hoverboy was an openly racist superhero who opposed immigration and fought the Japanese as a threat both within and outside the United States. In one issue, he helped the military chase down a Japanese-American who escaped from an internment camp, and accuses him of being guilty of "being a Jap."
In the '50s, Hoverboy was revived as a propaganda cartoon fighting Communist Koreans with just as much subtlety. Just kidding. In reality, Hoverboy was actually created in 2000 as a short satirical film by the National Film Board of Canada, written and directed by Marcus Moore. The allegedly classic cartoon is a scathing satire of racism and propaganda in the era.