6. 1930: Betty Boop Gets Sexed Up (and Shot Down)

During the early days of animation, Disney’s studio wasn’t the only one having trouble defining its characters’ personalities. Max Fleischer (creator of Popeye) also had a giant hit on his hands with the seductive, garter-wearing flapper Betty Boop. However, some theater managers began reporting that their conservative audiences found the pint-size coquette too risqué, and in 1935, Betty became the first cartoon character to be censored by the Hays Office. Forced to make a change, Fleischer responded by transforming her into a more wholesome and domesticated lady. Sadly, the makeover proved fatal. By the end of the decade, Betty had fallen into her own Great Depression, never to be heard boop-boopy-dooping again.

7. 1933: Toons Get Looney

Four of the most original and creative artists ever to come along—Tex Avery, Chuck Jones, Friz Freling, and Robert McKimson—had a different philosophy when it came to their animated creations: the zanier, the better. As the minds behind such classic characters as Daffy Duck, the Tasmanian Devil, Elmer Fudd, and Bugs Bunny, the animators made sure their stars ran wild, shouted at the top of their lungs, and killed, maimed, blew up, slugged, shot, and destroyed their foes. They even dressed ’em up in drag when the occasion called for it. As the Warner Brothers slogan promised at the beginning of each film, these were, indeed, Looney Tunes.

But it wasn’t just their wackiness that made the Looney Tunes the largest collection of animated stars any studio had ever created. It was their animators’ inventiveness. Bugs and Daffy were two of the first characters aware of their own cartoon-ness, which meant they were not only characters, but actors, as well. And while Felix the Cat may have been able to turn his tail into a baseball bat, Bugs Bunny could play pitcher, catcher, umpire, and himself all at the same time.

8. 1941: Animators Strike Back

Snow White and the Seven Dwarfs might have had a happy ending, but for the animators working behind the scenes, things were less than fairytale. Cramming to meet the film’s deadline, many artists worked well into the night with the understanding that they’d get bonuses once the film earned back its money. The film grossed oodles, but instead of doling out bonuses, Disney earmarked his handsome profits for a new studio he wanted built in Burbank. Fighting back, the Screen Cartoonists Guild went up against the Disney powerhouse in 1941. The ensuing strike lasted more than two months, and it took a White House intervention to halt it. The dispute was only settled when F.D.R. sent in mediators and forced Walt to cave.

Although the strike served as a disappointing reality check in the animation world, it ultimately sparked a series of positive changes in the industry. Artists were finally given on-screen credit for their work, and wages for 40-hour weeks doubled.

9. 1942: X Marks the Rating

At times, the Warner Brothers’ lunacy knew no bounds. During World War II, they created racy cartoons solely for American soldiers stationed in Europe. Full of expletives, X-rated images, and the occasional scatological humor, these animated shorts featured an inept trainee named Private Snafu. Amazingly, one of Snafu’s writers was Ted Geisel, better known as Dr. Seuss.

Other wartime WB cartoons created for regular civilian consumption featured edgy characterizations of Hitler and Mussolini that would never pass military muster today. For instance, in “Bugs Bunny Nips the Nips,” Bugs sells ice cream bars stuffed with hand grenades to Japanese soldiers he affectionately calls “Slant Eyes.” Not exactly politically correct by modern standards.

10. 1956: Cartoons Go Prime Time

Following the disillusionment of the Disney strike in 1941, hundreds of animators were motivated to set out on their own. Zachary Schwartz, David Hilberman, and Stephen Bosustow were three of the most notable Disney artists to take the opportunity to head in a new direction. The result was United Productions of America, better known as UPA.

Whereas every year Disney pushed its cartooning style further toward realism and literalism, UPA pushed its style toward contemporary art. Disney’s characters were soft and cuddly, while UPA’s were angular and almost cold. And while Disney was mainly interested in animating animals, UPA made humans the stars of its films—and it paid off.

One of its first big hits was Gerald McBoing-Boing (the brainchild of Dr. Seuss, who collaborated with UPA on the series), which beat out both Tom & Jerry and Mr. Magoo for the 1951 Oscar. In 1956, CBS turned the film short into a Sunday afternoon TV series. And although the show didn’t last nearly as long as later animated series such as The Flintstones, McBoing-Boing—and the UPA animators—have had a huge impact on the world of animation. From the minimalist backgrounds of Spongebob Squarepants to the flat, cutout look of South Park, the studio has influenced more than a half-century of cartoons by showing animators that it’s OK to avoid realism altogether.