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TV Shows You Didn't Know Share A Universe

There's nothing quite like getting into a good TV show. Whether we're tuning in week after week or binging the whole thing at once, the characters we've come to know and love over time can start to feel like our best friend or even our mortal enemy. And every once in a while when the stars shine just right, the television gods smile upon us by bringing together two or more of our favorite TV shows.

As the writing wizards behind Marvel know all too well, whether it's in the form of shared lore, character swaps, or that holy grail of network television the crossover episode, there's nothing quite as mind-blowing as realizing that two beloved TV shows are set in the same shared universe. And apparently, TV writers love writing it just as much as we enjoy watching it because more television shows than most of us realize are set in expanded TV universes. From sitcom swaps to mystery mashups, check out these favorite TV shows you didn't know share a universe.

Homicide: Life on the Street and Arrested Development

In the vast world of police procedurals, one fictional detective — Richard Belzer's Detective John Munch — has managed to drift throughout the wider television multiverse over the past few decades including, surprisingly, the world of "Arrested Development." According to Dick Wolf, who created "Law & Order," the whole thing started when he and Tom Fontana of "Homicide: Life on the Street" struck up a friendship while working in the same building during the late '80s (via TelevisionAcademy.com). Despite their two shows being quite different, Wolf says the pair dreamed up a crossover "mostly for the annoyance factor." Even if the actual implementation turned out to be "logistically a nightmare" and NBC didn't want to pay for it, the crossover was such a success that it turned out to be just the beginning of Munch's world-hopping.

Through the years, Munch appeared in 10 different TV shows, crossing into different networks, genres, and styles of television including "Arrested Development." In the critically-acclaimed comedy series, Munch shows up undercover as part of a CIA sting operation disguised as a scrapbooking class teacher with designs on getting dirt on the Bluths. Including the detective's other appearances, this would mean the same wider universe includes "The X-FIles," "The Beat," "The Wire," and "Law & Order."

Love Boat and Fantasy Island

If you were in the market for feel-good storytelling in a vacation setting during the late 1970s to early '80s, "Fantasy Island" and "The Love Boat" had you covered. Set on the dreamy MS Pacific Princess, "The Love Boat" followed guests as they set sail on the high seas, their minds on adventure and their course on a new romance with help from Captain Stubing's friendly crew. For most of its run, the series was lined up back-to-back with "Fantasy Island," which found Ricardo Montalbán of "Khannnn!" fame starring as the enigmatic Mr. Roarke who, with help from his sidekick, Tattoo (Hervé Villechaize), and seemingly supernatural forces to bring guests' fantasies to life — usually along with a valuable life lesson.

With such similar settings and themes, it was only a matter of time before viewers got confirmation that the two shows share a universe. It would come in a 1980 episode of "Fantasy Island." After seeing off a pair of guests, Tattoo pulls out a photo of the Pacific Princess, telling Mr. Roarke it's his fantasy to visit the Love Boat. Although Mr. Roarke says he's not sure if he can get Tattoo on board, he promises to bring the boat to Tattoo someday soon. Seeing as Vicki (Jill Whelan) of "The Love Boat" would later pull out a photo of Fantasy Island, it's safe to say the two vacation destinations exist in the same fictional universe even if we never did get to see Tattoo make that pleasure cruise.

Bones and Sleepy Hollow

Throughout its 12 seasons on the air, the lighthearted cozy mystery-meets-forensics procedural, "Bones," was more than just a character-driven comfort show. It also gave viewers a chance to get an inside look at the world of forensic archaeology and anthropology with the help of Dr. Temperance "Bones" Brennan's (Emily Deschanel) team of science geeks at the Jeffersonian Institute Medico-Legal Lab located in Washington, D.C. And thanks to two very special crossover episodes, it turns out supernatural shenanigans are canon in the "Bones" universe.

Like "Bones," the supernatural horror, "Sleepy Hollow," picked up an avid following during its short run thanks to its witty writing, rich lore, and memorable ensemble cast. The fish-out-of-water tale found Revolutionary-era Renaissance man Ichabod Crane (Tom Mison) facing off against demonic forces working to bring about the apocalypse. Although the series was not moved to the D.C. area until its fourth season, fans of both shows were treated to a Halloween crossover tale beginning with the Season 11 "Bones" episode, "The Resurrection in the Remains," and wrapping up in the Season 3 "Sleepy Hollow" episode, "Dead Men Tell No Tales."

The expanded universe actually contains three series thanks to the short-lived "Bones" spin-off series, "The Finder," a Florida-based tale of a retired army sergeant whose TBI inexplicably grants him the near-supernatural ability to locate just about anything.

Cold Case and CSI: New York

One of television's most long-running procedural franchises is the "CSI" universe. First originating with the 2000 premiering series, "CSI: Crime Scene Investigation," the franchise would spend 15 seasons on the air, spawning several spin-off shows including "CSI: Miami," "CSI: NY," "CSI: Cyber," and "CSI: Vegas." Through the years, this has yielded its own set of in-franchise crossovers like the three-part "CSI: Trilogy" crossover that spanned "CSI," "NY," and "Miami." But it's also part of a larger shared universe that includes "Cold Case," "Without a Trace," and weirdly, "Two and a Half Men."

The first in the trio of non-CSI crossovers, "CSI: NY" and "Cold Case" crossover episode, "Cold Reveal," begins when Philadelphia detective Scotty Valens (Danny Pino) of "Cold Case" reveals DNA from "CSI:NY" detective Stella (Melina Kanakaredes) came up in a Philly cold case. In pursuit of answers, he travels to the Big Apple, where the two detectives end up searching for the truth together. The show's parent series, "CSI," would later cross over with "Without a Trace" in a two-part episode spanning both shows. And in 2008, a two-part crossover featuring "CSI" and "Two and a Half Men" would officially put the collective "Cold Case," "Without a Trace," and "CSI" universe in the world of the popular sitcom.

Pretty Little Liars: Original Sin, Riverdale, and Chilling Adventures of Sabrina

The world of Archie Comics has come a long way since it first arrived on the scene in 1941. The flagship series, "Archie," featuring all-American teens Archibald "Chick" Andrews, Betty Cooper, and Jughead Jones, would lead to a much wider comic book universe that includes Josie and the Pussycats and Sabrina the Teenage Witch. Over the years, a whole slew of adaptations would arise from the Archieverse from animated TV shows like "Sabrina: Secrets of a Teenage Witch" to the film adaptation of "Josie and the Pussycats." But the franchise took a much more creative departure with its 2017 supernatural horror and crime drama series, "Riverdale," adapted for The CW by Roberto Aguirre-Sacasa.

First envisioned as a John Hughes-inspired teen adventure, the concept for the Archieverse story "Riverdale" would (thankfully) evolve into something more David Lynchian before hitting the airwaves. "Chilling Adventures of Sabrina" was meant to serve as a companion series, with Sabrina (Kiernan Shipka) even making an appearance on Riverdale on Season 6 of the series. And according to Roberto Aguirre-Sacasa, both shows share a universe with "Pretty Little Liars: Original Sin" and presumably, its parent series, "Pretty Little Liars."

Although brief, the reference comes when the Liars' investigation leads them to a clue involving "the Sisters of Quiet Mercy over in Riverdale." Confirming the connection, Aguirre-Sacasa told TVLine the writers didn't know if they could leave the reference in, but since no one objected, "I guess it does exist in the same universe." Fan theorists, go wild.

Magnum, P.I. and Murder, She Wrote

With his tiny shorts, party-ready mustache, wealthy benefactor, and candy apple red Ferrari, Thomas Magnum (Tom Selleck) of "Magnum, P.I." epitomized 1980s cool detective aesthetic as he mosied all over Oahu chasing down the latest private investigation. Magnum's energy was pretty much the polar opposite of another 1980s detective, Maine-based retired teacher-turned-mystery writer, Jessica Fletcher (Angela Lansbury), of "Murder, She Wrote." But the two shows have more in common than their status as network hits or the fact that they both have commas in their names – they also exist in the same TV universe.

In a two-part crossover episode spanning both series beginning with the "Murder, She Wrote" episode, "Magnum on Ice," and ending in the "Magnum" episode, "Novel Connection." The two-parter sends Jessica to Hawaii after Magnum is accused of a murder-for-hire plot, and the pair end up working together to find the real killer. "Magnum" also shares a connection with "Simon & Simon" through a similar two-part crossover. Although rumors of a planned "Magnum, P.I." and "Quantum Leap" crossover that have haunted the Internet for decades seem to be just that, the fact that the Simons, Jessica Fletcher, and Thomas Magnum are all out there solving mysteries in a shared universe still makes for some pretty fun storytelling.

Family Guy and The Simpsons

The creators of "South Park" may find "Family Guy" exasperating, but "The Simpsons" team seems to have a more magnanimous take on their fellow Fox animators, with the two shows occasionally engaging in some back-and-forth shout-outs that go beyond mere references or parodies through the years. For Seth MacFarlane and company, who owe a debt of gratitude to the elder series, the chance to take those references up a step with a full-fledged hour-long crossover episode in 2014 must have been a dream come true.

In an Entertainment Weekly interview with "The Simpsons" creator, Matt Groening, MacFarlane credited "The Simpsons" with inspiring his path forward, emphasizing, "I'm the first person to say, stylistically, absolutely, we took 100 cues from The Simpsons." According to the "Family Guy" creator, Rich Appel, who variously worked on both series, spearheaded the team-up — a "Family Guy" episode in the style of "The Simpsons" featuring characters from Springfield.

The episode follows the Griffins as they travel to Springfield, where they cross paths with the Simpsons. While Peter and Homer search for the Griffins' car, Bart and Stewie end up making prank calls together, Lisa connects with Meg, and Marge and Lois find they have a lot in common when it comes to their husbands. While hardly the best episode in the two shows' runs, "Simpsons Guy" was a dream come true for fans of both shows while establishing their place in the same TV universe as canon.

Eureka and Warehouse 13

These days, there aren't nearly enough quirky, episodic sci-fi and fantasy shows on the air. But from the mid-aughts through about 2016, fans of this lighthearted fare could find a wealth of it in shows like "The Librarians," "Haven," and "The Magicians." So the fact that two of the more beloved SyFy series in that category, "Eureka" and "Warehouse 13," exist in a shared universe meant fans of the genre were constantly in for a treat. And it makes sense since their stories seem to go together naturally.

Set in the town of Eureka, Oregon, "Eureka" is set in a secretive world populated by the scientific geniuses behind Global Dynamics, the company responsible for some of humanity's most recent technological breakthroughs. "Warehouse 13" deals with a pair of U.S. Secret Service Agents tasked with rounding up supernaturally charged artifacts and storing them in their own secret HQ. Their shared universe is referenced throughout both TV shows, going far beyond the occasional cameo or casually-dropped reference. Eureka researcher Douglas Fargo (Neil Grayston) shows up at Warehouse 13 more than once ("13.1," "Don't Hate the Player"), and Warehouse 13's Claudia Donovan (Allison Scagliotti) and Hugo Miller (Rene Auberjonois) make their own journeys to Eureka ("Crossing Over," "13.1").

Full House and Family Matters

Anyone who had access to network television during the '90s will likely feel a wave of nostalgia at the mention of ABC's TGIF (Thank Goodness It's Funny), the Friday night sit-com block responsible for generating a host of laugh-tracked TV shows. With their Randy Newman theme songs, inoffensive family-friendly comedy, and occasional Very Special Episodes, these TV shows were the perfect way to round off the week by tuning into the latest shenanigans of an unconditionally loving All-American family. Viewers stopped by each week to check in with odd-couple cousins Larry Appleton (Mark Linn-Baker) and Balki Bartokomous (Bronson Pinchot) or see what Coach Lubbock's (Bill Kirchenbauer) oversized family was up to that week on "Just the Ten of Us."

But only the most dedicated TGIF viewers knew that all their favorite TV shows were actually set in the same TV universe, with many of them spinning off from other series in the lineup. And occasionally, they'd even get treated to the ultimate sitcom experience: the crossover episode, like when Steve Urkel (Jaleel White) from "Family Matters" dropped by to visit the Tanner family in the 1991 "Full House" episode, "Stephanie Gets Framed" to ask for cheese, strut with Jesse (John Stamos) and offer a freshly bespectacled Stephanie (Jodie Sweetin) some terrible advice. Thanks to this and other crossovers, the list of TV shows set in the same universe would become fairly expansive, eventually including series like "Step By Step" and "Boys Meets World" while fueling fan theories like the Grand Steve time travel theory thanks to Urkel's canon time travel machine.

Ally McBeal and The Practice

Former Boston-area attorney-turned-TV producer David E. Kelley has been responsible for bringing some of television's best dramas to the small screen over the years in shows like "Chicago Hope," "Picket Fences," and "Big Sky." Falling under the category of "write what you know," several of his most popular productions are set in Boston and happen to be part of a shared TV universe. First airing in 1997, "Ally McBeal" was ahead of its time as a pioneer of cringe and surreal comedy. Starring Calista Flockhart, the series found its eponymous character navigating the strange sexual politics of a Boston law firm with a unisex bathroom.

Premiering the same year, "The Practice" was a comedy-drama also set in a Boston law firm that starred Dylan McDermott as its ethically torn partner Bobby Donnell. Canonizing their shared universe, both shows would share quite a few characters including Boston judges Seymore Walsh (Albert Hall), Jennifer Cone (Dyan Cannon), and Roberta Kittelson (Holland Taylor).

Main characters from both shows would also cross over to the other series from time to time, as when most of the main cast from "The Practice" stopped by "Ally McBeal" in the Season 2 episode, "Axe Murderer." Taking into account crossovers and spinoffs across the Kelleyverse, the wider universe includes a handful of other series including "Boston Public," "Boston Legal," and the medical drama, "Gideon's Crossing."

Star Trek and Team Knight Rider

When TV writers reference other works that have influenced their storytelling, it can add layers to the storytelling or even lead to new fan theories like when Walter Bishop (John Noble) of "Fringe" mentions the glasses he got from Dr. Jacoby (Russ Tamblyn) of Washington, teasing that "Fringe" exists in the "Twin Peaks" universe. While they're usually a treat, occasionally fans get a clumsily-handled TV allusion that feels shoehorned in, leaving fans scratching their heads at why writers worked so hard to force something that didn't feel right. Such is the case with the Trek Rider connection when an episode suggests "Star Trek" and "Knight Rider" share a universe.

This connection begins with the 1967 "Star Trek" episode, "The Changeling," which found the Enterprise crew dealing with the deadly sentient space probe, Nomad, which originated from Earth. When the probe mistakes Jim Kirk's (William Shatner) name for his creator, Jackson Roykirk (Marc Daniels), it realizes that, like everything else it's meant to destroy, Nomad itself is imperfect and must itself be destroyed.

It's easily one of the best stories in the Trek universe, with TIME Magazine even voting Nomad as one of the franchise's best villains in 2016 — which is apparently why the writers of "Team Knight Rider" tried to write it into their show. One episode in the "Knight Rider" sequel deals with a killer sentient space probe invented by none other than one Jackson Roykirk. While it's a one-sided reference, it's still enough to warrant shipping K.I.T.T. with the Enterprise computer.