Some cartoon characters have been with us for so long, we probably feel like we know them as well as we know members of our own families. But, just like a real person, these iconic animations come with a whole lot of history and baggage that we've either forgotten all about, or just never paid enough attention to in the first place. Sometimes, these changes happen to freshen up a character for a new generation. The longevity of classic Disney, Hanna-Barbera, Cartoon Network and Nickelodeon creations depend on a cycle of constant reinvention.

A character you watched on TV while munching your cereal every Saturday morning as a kid has probably gone through at least two or three alterations by now that are so radically weird they'll make you spit that cereal right out. In other cases, the opposite is true. Characters who we think of as entirely wholesome, like Mickey Mouse and Donald Duck, actually have quite a few politically incorrect skeletons lurking in the Disney closets from a bygone era; characters who we think of as entirely silly, like Bugs Bunny, have actually been taken very seriously in the past; and characters who we think of as just being talking dogs like Scooby-Doo... Well, you're in for a bizarre surprise with that one.

15 SCOOBY-DOO IS WAY MORE THAN A TALKING DOG

Scooby-Doo Twin Peaks

There are a lot of questions we need answered about the Mystery Gang's canine mascot. How old is he by now? Is Shaggy the only one who can understand him? How does he have his own personal brand of treats? And, how come he can talk like a human? Well, the first three you'll have to investigate yourself. As for that last one? Get ready for the weirdest explanation imaginable.

According to the Scooby-Doo! Mystery Incorporated continuity, the easily shaken pooch is descended from an ancient race of interdimensional beings called Anunnaki. This ancient race can periodically cross over to our world, possess animals and speak through them like puppets, which is where Scooby's vocal talents come from. If that wasn't weird enough, the episode that reveals this origin also references Twin Peaks' infamous "Red Room" dream sequence.

14 DONALD DUCK IS AN EX-NAZI

Donald Duck Nazi

Donald Duck's past as America's premiere bird-based Hitler fan is pretty well-known. In 1945, Donald once appeared in full Nazi costume as part of a series of WWII propaganda cartoons. His infamous rage issues made him an obvious pick to mock the leader of the Third Reich, but it's an aspect of his past that still doesn't sit well with the fondness we have for him now.

Lesser known, however, is Donald's other, other side hustle as a family planning doctor. In 1968, Donald was put to political use again by Disney, this time in aid of a 1968 short for the ominously-named, US Population Council. Donald played a ditzy doctor advising Third World couples to have less kids because, as the bodiless narrator warned, too many children were being saved by improved healthcare to maintain "population balance."

13 REN AND STIMPY'S "BEACH PARTY"

The Ren and Stimpy Show was never known for playing it safe and staying within conventional boundaries. In fact, it chewed up and spat out as many of them as it could during its frenetic run between 1991 - 1995. Though creator Jon Kricfalusi seemed to get away with an awful lot of crude humor and gross-out scenes, it seems he didn't get away with everything he wanted to.

His extra energy and ideas for Ren and Stimpy were channelled into his adult-orientated 2003 series, Ren and Stimpy: Adult Party Cartoon for Spike TV. One episode, "Naked Beach Frenzy" pretty much plays like an adult film parody of the original kids show, with excessively large parts of the female anatomy bouncing around everywhere, and Ren even using a certain part of his own anatomy as a, um, towel rack.

12 ROBIN'S DISTURBING FAMILY KEEPSAKE

Teen Titans Go! Robin II Urn

Teen Titans Go! has been splitting fan opinion since it started airing in 2013. One thing we can all agree the show excels at, though, is its ability to pack references and Easter Eggs into every episode. The episode "Sidekick" from Season One is no exception, with so many in-jokes stuffed into one particular frame that you'd need to pause it to spot them all.

The frame in question happens when Robin places a family photo of himself and Batman on his bookshelf. Around it, we can spot Scarface the ventriloquist doll, a reference to Clayface's origin from Batman: The Animated Series, a Riddler plate, a box of Hush's bandages, and -- most disturbingly -- an urn marked "Robin II" and a crowbar. Are those the ashes of Jason Todd and the weapon that killed him? Now that's messed up, Robin.

11 BUGS BUNNY WAS IN THE MARINES

Bugs Bunny Marine

No, we're not just referring to an animated version of the Marines. The Warner Bros. mascot was a legit honorary officer of the real US Marines. Try and wrap your head around that. Bugs was inducted after he appeared as one in the 1943 short, "Super-Bunny." The cartoon was an obvious Superman parody, with Bugs gaining super powers from a "super carrot."

After his powers wear off, Bugs decides to become "a REAL Superman," heading into a phone booth, not to change into a superhero costume, but into a Marine uniform instead to go fight Eastern fascism. The US Marines made him an honorary Private -- he even had dogs tags made -- and, by the time he was discharged at the end of WWII, he'd reached the rank of Master Sergeant.

10 SHAGGY IS A VEGAN

Scooby Doo Shaggy Vegan

Other than his obvious predilection for mind-altering substances, we associate Scooby-Doo's closest human pal with one thing and one thing only: sandwiches. Big, meaty sandwiches. But, the character's food choices have actually proven contentious behind the scenes. Shaggy's best-known voice actor, Casey Kasem, was a strict vegan, which led to Shaggy turning vegetarian.

Kasem wasn't satisfied with this compromise though, and hated that Shaggy would carelessly eat anything and everything in sight. The final straw came when the actor was asked to voice Shaggy for a Burger King commercial in 1995. Furious, he refused, and even quit the role he'd been playing for over two decades, only returning to it in 2002 when the producer's finally agreed to make Shaggy a vegan.

9 THE MYSTERY OF GOOFY'S WIFE

Disney Goofy Mrs Goof

If you didn't already know -- yes, Goofy has a wife, and for such an incidental character, she sure has a lot of mystery surrounding her. The character known only as "Mrs. Goof" appeared in a series of shorts in the '50s with her husband, which went to great and strange lengths to never show us her true face. Because of this -- along with her caucasian flesh-coloured skin, hair and different number of fingers to Goofy -- many suspect she's secretly human.

This is despite her confusingly being described as an "anthropomorphic dog." Thanks to her absence in the '90s Goof Troop series and movie, some fans also claim she's been killed off. Disney's official answer to this (on its Disneyland FAQ page, strangely enough) is that "there's no definitive answer." She's your character, Disney -- how can you not know?

8 THERE'S A HIDDEN TRAGEDY IN THE DINK FAMILY

Doug The Dinks

With a super successful run that ended up spanning most the '90s, Doug is still fondly remembered to this day. Looking back though, it could be a pretty bleak show. The premise itself was a tough one that many kids could relate to -- moving to a new town and feeling out-of-place and uncomfortable around new people. Titular character Doug seemed to find more solace inside his own imagination than in the outside world.

Other sad aspects of the show were more hidden, like the fact that the adult couple who Doug was friendly with -- Mr. and Mrs. Dink -- betrayed the emptiness of their lives in their very names. The surname "Dink" was actually an acronym for "Dual Income, No Kids," implying that all the money and gadgets in the world couldn't make them truly happy in place of family.

7 OPTIMUS PRIME HATES MOTLEY CRUE

optimus-prime-transformers

Thanks to that killer soundtrack for the classic, '80s animated movie, The Transformers franchise has long been associated with the rockier side of the musical spectrum. This connection is bolstered, too, by its many musically-themed Transformers, like Soundwave, Blaster and Jazz. Knowing this, it's pretty funny that one of Optimus Prime's character quirks is that he's a massive music snob.

He particularly turns his nose up (or, at least, he would if he could...) at the music of hard rock legends Motley Crue, according to the letters page of #324 of the Marvel Transformers comics. This detail follows through into the cartoons, too, with Optimus often expressing his deep distaste for Blaster's passion for "good, hard, LOUD rock 'n' roll." What did Motley Crue ever do to you, Optimus?

6 TMNT'S RAPHAEL HAS A PHOBIA OF COCKROACHES

Raphael cockroach TMNT

Though all the Turtle brothers are fearless, Raphael is known for being the hardest and gruffest of the bunch; rarely one to walk away from a fight or let himself be easily defeated by anyone or anything. Except, as it turns out, if there's a cockroach involved. The 2012 series introduced fans to a new aspect of Raph's character: a debilitating fear of the little insects.

This phobia is actually a real one called "Katsaridaphobia." It was revealed that Raph suffered from it in the episode "Cockroach Terminator" in which the Turtles are hunted by a giant and seemingly indestructible cockroach that, at one point, has the quaking Raph cornered and begging for mercy. Honestly, as interesting as this is, it's a strange fear for a guy who was raised in a sewer.

5 SMURFETTE WAS A SPY CREATED BY GARGAMEL

Smurfette origin

To those who know their Smurf-story well, this one won't come as a surprise. For those who don't -- prepare to hear some odd home truths about what Smurfette really is. (Or, was at least.) The question of why Smurfette is the sole female Smurf in the village was never really a mystery at all. In Peyo's original comics, Smurfette wasn't a real Smurf to begin with -- she was created by Gargamel.

Gargamel sent her into Smurf Village as a seductive distraction to incite chaos amongst the male-dominated Smurf society (which she did.) She even had cool 007-style gadgets like a transponder disguised as a make-up compact to keep her boss in the loop. Eventually, the disgruntled Smurfs put her on trial for her evil-doing, leading to her suffering a crisis of conscience, and turning on her creator. Papa Smurf then used magic to make her an official Smurf.

4 FRED FLINTSTONE HAS A GAMBLING PROBLEM

Fred Flintstone gambling

Most people know about that infamous 1960 Winston cigarette commercial starring Fred Flintstone and Barney Rubble. But, did you know The Flintstones were also used to sell booze, too? In 1967, Fred and Barney also popped up in an ad for Busch Beer. Of course, smoking and drinking aren't too shocking as vices. But, Fred's gambling addiction was a recurring issue in the show.

In the 1962 episode, "The Gambler," Fred's addiction -- that was thought to have been cured -- resurfaces with a vengeance, resulting in him losing furniture and appliances to his enemy, Arnold the paperboy. Eventually, Wilma has to intervene to try and stop him from gambling away everything in their home. Fred being a member of the "Loyal Order of the Water Buffalos," a spoof of secretive fraternities like the Freemasons, did little to curb his bad habits, either.

3 TOMMY PICKLES MIGHT SECRETLY BE AN ALIEN

Invdader Zim Plague of Babies

The Rugrats kids are anything but normal infants when their unsuspecting parents aren't around, but, according to Invader Zim's writers, there might be even more to them than we ever realized. The Invader Zim episode, "Plague of Babies" was inspired by the cult, British horror movie, Children of the Corn, featuring an invading alien force that disguised themselves as human infants.

The original plan for the episode was to use The Rugrats' Tommy Pickles as their leader. Tommy's voice actor, E.G. Daily even agreed to be in it. Considering both were Nickelodeon shows, you'd have thought this would have been doable, but, apparently not. The network couldn't sign off on the crossover because of "copyright issues." The character was renamed "Schnooky" but you can still see a lot of Tommy in the final design.

2 THE TINY TOONS GET REKT

Tiny Toons Beer

While Fred Flintstone encouraged adults to knock back a cold, Busch Beer, Tiny Toons did its best to ensure that kids would never want to touch a drink in their lives. In a segment simply entitled "Beer" at the end of the episode, "Elephant Issues," Buster informs Plucky and Hamilton that they're going to give kids a demonstration of the dangers of alcohol.

They then have a sip of beer, take a cop car for a joyride and end up nosediving off of "Death Mountain." Their souls float up to Heaven (just to hammer home the permanence of death) and tell kids they hope the message was received. Oh, we think it was, guys. Loud and not-so-subtlety clear. Ironically, the PSA was pulled by Fox in 1991, a ban that was only lifted 23 years later in 2013 when it re-aired on the Hub Network.

1 MICKEY MOUSE USED TO BE A PREDATOR

Mickey Mouse Plane Crazy

Mickey Mouse is one of the most -- if not, the most -- recognizable animated characters in the world. He was one of Walt Disney's earliest creations and became the flagship character for his company, embodying the inoffensive and loveable qualities that the brand aspires to. But, even a critter as wholesome as Mickey doesn't come with a spotless record.

In his younger years, Mickey's courtship of his long-time gal pal Minnie left a lot to be desired. In the 1928 black and white short, "Plane Crazy," Mickey acts like a sex-starved lunatic; desperately trying to steal a kiss from Minnie, and when she refuses, threatening to crash the plane that they're in until she becomes scared enough to give in. A terrified Minnie bails on the date mid-air and gives him a well-deserved slap.