South Park has always been known for being one of the most controversial shows on television, whether we're talking about animated shows or live-action. Luckily for it, it's had a major influence on adult animation as a genre, since it's pushed the envelope further than pretty much any other television show that's been on the air, at least in the genre of comedy.
While there have been plenty of shows to bite the style of South Park, none of the direct competitors have been able to touch it when it comes to outrageous comedy, but there are a ton of characters we've gotten as a result that would fit in perfectly in the sleepy mountain town.
Brian Griffin
Brian Griffin is a self-insert for Seth Macfarlane, a liberal-leaning man and the creator of the series Family Guy which the character comes from. While South Park purports that it makes fun of everyone equally, Matt Stone and Trey Parker are well-known members of the Libertarian Party, which is definitely on the right if we're talking about the binary political spectrum.
It would be interesting to see Brian of all characters on the show appear in South Park, especially since he's probably the most grounded character in the show despite being a talking dog.
Butthead
Butthead is one of the titular characters of Beavis And Butthead, an incredibly popular MTV show that spent its time lampooning teenagers and counterculture while at the same time catering to the very audience it was a parody of.
While ideally, the pair would show up, Butthead is definitely the more sociopathic of the pair, which means it would be rather interesting to see how he'd pair up with Eric Cartman, who might even be more deviant than he is. Maybe a plotline where Butthead appears as a role-model for Cartman but learns a thing or two about being awful along the way would be ideal.
Abraham Lincoln
While strangely enough, Clone High is much less political than one would assume it is, especially in comparison with South Park, the two shows have a pretty similar style with reference to the fact that both of them start with political premises often only to subvert the direction of the show the and expectations of the audience.
Thanks to a bunch of soundbites being used on TikTok recently, the Clone High fandom has received a resurgence, and the voice actor for Abraham Lincoln is Will Forte who seems like he would definitely be up for a crossover were it possible. Abraham Lincoln seems like he would fit right in as an upperclassman at school.
Nathan Explosion
We've seen plenty of musicians lampooned or appearing in South Park from the entirety of Radiohead to Michael Jackson. That being said, there haven't been too many fictional musicians featured on South Park and we think it's time that Matt and Trey change that. Where else would be better to grab a musician from than Metalocalypse.
For those not familiar, Metalocalypse is probably one of the best cult classics that Adult Swim has ever put out, centering around a dysfunctional Death Metal band called Dethklok with way too much money. Nathan Explosion would be an excellent addition to the show, at least for an episode or two, as he'd surely introduce some gore and mayhem to the town.
Carl Brutananadilewski
Carl from Aqua Teen Hunger Force (who's last name won't be rewritten here) is a character who one could very easily see existing in the universe that's established in South Park. The character is churlish, rude, gross, and incredibly crude, just like most of the characters we encounter in the show.
And even if the Aqua Teens don't actually show up in such a crossover episode, Matt and Trey could probably use the exact format that's frequently shown in Aqua Teen and have the kids ruin his house and annoy him to wit's end, probably in some scheme that's been cooked up by Cartman.
Roger
Roger is one of the main characters of American Dad! in addition to probably being the most noteworthy character in the show. As the show has progressed, there's been a shift from centering around the main family towards focusing on Roger, which only makes sense considering the character's whole schtick is the fact that he's trying to hide his true identity by constantly adopting new characters and personas, making for an endless array of comedy material.
If he were to show up in South Park, no one would be all that surprised, nor would it even be outside of the realm of possibility since the very first episode of the show is entitled "Cartman gets an anal probe".
Brock Samson
Brock Samson is probably one of the most loved characters in modern underground adult animation, and pretty much everyone's favorite from the cult classic The Venture Bros.
He's the longtime bodyguard of Hank and Dean Venture, who are the sons of Dr. Thaddeus "Rusty" Venture, a scientist who's the target of tons of different villains across the world. Hank and Dean Venture would be a super fun cameo, but along with them comes Brock, and since the boys are generally pretty wholesome, they'd most likely be a quick target for Cartman.
Rusty Cuyler
Since the boys in South Park are already friends with a sentient towel, it's probably not an entire impossibility that they could end up hanging out with "Appalachian Mud Squids", although it's not entirely clear that they're native to small-town Colorado.
For those not familiar with the show, one of the creators of Squidbillies was also one of the people behind Aqua Teen Hunger Force, which should hint at the surreal type of humor encountered when it comes to the squids. Rusty Cuyler, the son of Early would fit in with the boys pretty well, especially Kenny since he's been raised in a similar environment to Rusty.
Milo Oblong
An oft-forgotten gem of the Adult Swim catalog which oddly enough features an early role for Will Ferrell who's now famous for starring in movies like Step-Brothers and Anchorman. The show is created by a man who goes by the name of Angus Oblong who wrote a book that garnered his initial fame entitled "Creepy Susie and 13 Other Tragic Tales for Troubled Children".
The characters in The Oblongs are drawn from this book, from the main family to a few others, and the fact that the town in the show features people constantly exposed to radiation sounds like something straight out of South Park. One of the main characters, Milo, has a good heart just like Stan, with who he'd probably get along pretty okay.
Huey Freeman
With the fact that there very well could be a new revival of the now-classic Adult Swim series The Boondocks on the way, it would definitely make sense for the show that there could be a crossover between South Park and The Boondocks. The only issue is that like we've mentioned before, South Park actually leans to the right despite the fact that it presents itself as being divorced from the political spectrum.
The Boondocks, as anyone who's familiar with the show probably knows, leans super far to the left in comparison to pretty much most of the shows we see on the air. That being said, Huey Freeman is wise beyond his years and incredibly well-educated. He could handle pretty much anything the boys (probably Cartman) could throw at him, in addition to his martial arts prowess.