Crossover episodes are nothing new. Some are done as part of sweeps week, some are done in an attempt to boost ratings, but what the people writing these episodes probably don’t realize is that they’re helping to connect the entire television universe. Over the years, people including a comic book and television writer named Dwayne McDuffie, have spent far too much time finding the links between shows, proving that, basically, everything is connected.

10Homicide to The Wire

Homicide to The Wire

Let’s start out with two of the most gritty, realistic crime dramas ever written. Both were penned by David Simon, so it’s not really shocking that they would crossover at some point, particularly since they’re both about Baltimore cops. They only cross over briefly in a late episode of The Wire, with a cameo by actor Richard Belzer, portraying his character of Detective John Munch.

Munch is based on real-life cop Jay Landsman, who not only has a character named after him on the show but plays a completely different character of his own, a cop named Dennis Mello.

9Homicide to Law and Order

Homicide to Law and Order

Right here is where we begin to realize that John Munch is one of the two most important characters in this unifying television universe theory popularized by McDuffie. We aren’t even going to get into the time Munch popped up on Arrested Development, tying that world with all of the rest. Anyway, in what was a then-unprecedented move, when Homicide ended, the character of John Munch was brought into the cast of Law and Order: SVU.

He had also appeared, alongside a few of his fellow Baltimore detectives, on a couple episodes of the original Law and Order. Of course, this is already making things a little wonky in terms of continuity, considering virtually everyone in the cast of The Wire made an appearance on Law and Order as either a suspect, a victim, or a lawyer at some point.

8Homicide to X-Files



But you know what’s even weirder than the fact that everyone in The Wire was also someone else in the Law and Order universe, despite both characters existing simultaneously? The fact that, apparently, they also existed in the same universe as The X-Files. That’s because in the fifth season of that show, Detective Munch pops up to interrogate the conspiracy theorists who often helped out Mulder and Scully, known as the Lone Gunmen.

They later got their own spinoff show, and characters from The X-Files also popped up on the show Millenium, meaning all kinds of weird stuff was going on in this giant TV universe. But it’s about to get even weirder.

7X-Files to The Simpsons

X-Files to The Simpsons

And that’s because the characters of Mulder and Scully popped up in an episode of The Simpsons, meaning that, apparently in this grand, interconnected television universe, people can slip between live-action and animation pretty easily. Which actually holds with Simpsons canon since Homer found himself in a live-action world during one Halloween episode.

The Simpsons can also be connected to the show Family Guy, and thanks to the unofficial crossover with South Park called Cartoon Wars, that means that Eric Cartman lives in the same universe as Dana Scully. And also, it turns out, Cliff Claven.

6The Simpsons to Cheers

The Simpsons to Cheers

In another episode of The Simpsons, Homer is searching out a new bar after having been banned from Moe’s Tavern. He tests out a few different gin joints before finding himself in the place where everybody knows your name, with the actual cast of Cheers voicing their respective animated characters.

Of course, then you take into account the fact that Frasier alums Kelsey Grammer, David Hyde Pierce, and John Mahoney all voiced characters on The Simpsons and the connections get even better. Oh, and by the way, it’s David Hyde Pierce who helps connect Cheers to, eventually, Seinfeld.

5Cheers to Caroline in The City


People probably don’t really remember Caroline in the City, but it’s an important cog in connecting so much of this television universe since it’s the link between Cheers and, by extension, The Wire, Law, and Order, and The X-Files. Anyway, during one episode of Caroline in the City, the titular character – a comic strip artist – writes a strip and then we cut away to Seattle, into the apartment of Frasier Crane.

It’s here we see Frasier characters, Daphne and Niles, reading the strip and disagreeing on whether it’s funny. And since Frasier is obviously a spinoff of Cheers, that gives us yet another connection.

4Caroline in The City to Friends


But Caroline in the City didn’t stop there, either, as it also crossed over with Friends, the behemoth Must See TV Show about attractive white people. The crossover actually didn’t occur on the show Friends, because obviously that show didn’t need the ratings. Instead, Matthew Perry’s character of Chandler Bing stopped by Caroline in the City.

The main character of Caroline actually sort of indirectly stopped by Friends, but Leah Thompson more or less just made a cameo in the background of one episode. However, this connection just goes to getting us one step closer to connecting the Seinfeld world with the rest of this universe.

3Friends to Mad About You


That’s because Friends crossed over with the show Mad About You – which, by the way, also crossed over once with the Dick Van Dyke Show, so there’s yet another world that exists within this same universe.

Lisa Kudrow was pulling double duty with NBC, appearing on both Friends as one of the stars and in a minor role on Mad About You. Well, they decided to make a gag in which those two characters, it turns out, were actually twin sisters, and the character from Mad About You popped up several times on Friends.

2Mad About You to Seinfeld


But Mad About You wasn’t done connecting shows just yet, since it’s the linchpin to getting Jerry, George, and the rest of the Seinfeld crew linked to The Simpsons and The Wire. That’s because it was revealed on an episode of Mad About You that Paul Reiser’s character, a newlywed on the show, still had the lease on his old apartment.

That apartment he had? Well, it just so happened to be the one that would eventually be occupied by Cosmo Kramer, meaning that in this universe, the guy from Mad About You was Jerry’s old neighbor. Of course, there’s a little bit of a continuity hiccup here, since later in Seinfeld’s run, a gag involves George hating the show Mad About You. That said, it kind of makes sense if you consider the idea that everything happening is in the mind of a child anyway.

1Cheers to St. Elsewhere


And this is really where everything starts and ends because an incredibly popular theory online is that every television show ever created is really just taking place in the mind of an autistic kid named Tommy Westphall, who was a patient on the series St. Elsewhere.

We’ve barely scratched the surface with these connections, but thanks to a simple crossover between St. Elsewhere and Cheers, in which the doctors from St. Elsewhere find their way into Sam Malone’s bar, we’re able to posit that everything from the gritty, real-life drama of Homicide and The Wire exists in the same universe as The Simpsons. Just think, we didn’t even get into the connections to M*A*S*H, the Andy Griffith Show, or I Dream of Jeannie.