For many experts, Wilhelm Busch is considered the founding father of the comic. The artist from rural Germany inspired the first modern comic illustrators in New York and later even Walt Disney himself. His "heroes," which he began drawing in the 1860s, are mean animal torturers, drunk priests, bigots and two very naughty boys: Max and Moritz.

Not only the Comic Con, but also a Frankfurt museum, Kunsthalle Schirn, is exploring the genre this summer. The exhibition mainly features American comic pioneers, including Cliff Sterret. Pictured is Sterret's "Polly and Her Pals." The show demonstrates that the illustrators were part of an avant-garde movement that developed its own art form and anticipated Surrealism and Expressionism.

The rise of comics can largely be attributed to newspapers. The sinking price of paper and technically improved printing machines made it possible for newspapers to up their printing runs and reach mainstream audiences in the early 20th century. As publications competed for readers, comics played a central role. The success of a newspaper was often determined by the popularity of its comics.

In 1933, at the age of 14, Jerry Siegel and Joe Shuster created Superman and dubbed him the Hebrew word "Kal-El," which roughly translates as "voice of God." It took them five years to find a publisher. Finally, in 1938, DC Comics published the first Superman comic in the "Action Comics" series. That first edition was auctioned for $3.2 million (about 2.4 million euros) in 2014.

Superman wasn't alone for long. He was quickly joined by Batman, Captain America, Wonderwoman, The Flash, and countless others to fight the bad guys - including Adolf Hitler. Yes, you read that right. During World War II, Superman & Co. were popular among American troops in Europe, where they took on the enemy of the day.

At the end of World War II, many superheroes disappeared - only the most popular managed to keep "their jobs." Rather than fighting dictators, they took on extraterrestrials and criminals like the Joker. Superman & Co. appeared in numerous cinema films, which boosted interest in the characters. Most recently, "Deadpool" (2016, pictured) retold the story of the Marvel character of the same name.

He's not a superhero, but is one of the most popular comic figures of all time. Walt Disney Comics first introduced Donald Duck in 1943, and illustrator Carl Barks played a large role in the choleric bird's fame. Over the next 20 years, he illustrated Disney comics nearly monthly, creating a large collection of friends for Donald. Scrooge McDuck was born in 1947 and Gladstone Gander in 1948.

While the US was a forerunner in some of the most internationally well known comics, European illustrators were equally active. The most famous European duo, Asterix and Obelix, were born from the pen of French artists René Goscinny and Albert Uderzo (pictured). Created in 1959, the Gauls appeared in 36 books, the last of which - "Asterix and the Missing Scroll" - just came out last year.

Created by Belgian illustrator Hergé in 1929, Tintin is a legend among Europe's comic figures. The reporter travels around the world with his dog and experiences outlandish adventures, which are told over 24 books. However, the series has been criticized for reflecting racist colonialist attitudes. In 2007, a Congolese student sued to stop the distribution of the album "Tintin in the Congo."

Yet another comic star from Belgium is cowboy Lucky Luke. The man who always had a cigarette hanging out of his mouth was created by illustrator Morris and first appeared in the magazine "Spirou" in 1946. The first Lucky Luke comic book was released in 1949. Morris also wrote 17 live-action screenplays featuring Lucky Luke, who was played by Italian actor Terence Hill in two of them.

It hasn't always been easy for comics. At times, they were thought to dumb down and be detrimental to young readers. In 1977, author Will Eisner (pictured) coined the term "graphic novel," in order to emphasize the literary quality of his comics. It was a smart move, because suddenly a broader group of more traditional readers became interested in stories told in pictures.

Unlike in comics, a graphic novel is a complete story and is published as a book rather than a magazine. As far as content goes, they're nearly the same. US illustrator Art Spiegelman shot into the bestseller lists with his graphic novel "Maus" in 1986 and received a Pulitzer Prize in 1992 - a first for a comic. "Maus" tells the moving story of Spiegelman's father, a survivor of the Holocaust.

Unlike in the major comic hubs, like France and the US, German readers were not as open to the genre. But in recent years, German comic artists - like Reinhard Kleist - have established themselves internationally. And the next generation of illustrators is already in the limelight. In "Three Stones" (2016), Nils Oskamp told his story of being the victim of right-wing violence in his youth.

Originally from Japan, mangas in Europe were decried for glorifying violence or being too sexually explicit in the 1990s. It wasn't until TV series like "Sailor Moon" that they gained widespread acceptance. In the late 1990s, "Pokemon" even sparked a manga boom in Germany.