Why have one TV show when you can have two? And why just have a regular TV crossover when you can have a really weird TV crossover? The TV crossover had something of a heyday in the 1980s and 1990s, when characters from popular programs on the same network would routinely cross paths with one another as must-see events made to boost ratings. But sift through the run-of-the-mill TV show collaborations and you’ll find some oddball crossovers that have taken place across the decades.

1. The X-Files and Cops

As a show, The X-Files was never too concerned with realism—unless one accepts that all variety of monsters and little green men really do exist. It was odd, then, that the show’s seventh season saw a crossover episode with Cops, one of the earliest reality TV shows. “X-Cops” starts off like a normal episode of Cops ... only to see Mulder and Scully intrude on the police’s hunt for what turns out to be an invisible monster that transforms based on the fears of its victims. The X-Files writer/producer Vince Gilligan had been trying to get a Cops spinoff episode made since season 4, but it took until season 7—when it looked like The X-Files might be headed toward cancelation—for showrunner Chris Carter to give him the go-ahead.

2. Alf and Gilligan’s Island

ALF has really gotten around. The cat-eating alien—star of his own sitcom between 1986 and 1990—has appeared in episodes of Young Sheldon, Blossom, and Matlock, to name a few. Back on his own show, the second season gave us a crossover with Gilligan’s Island. In the episode, titled “Somewhere Over the Rerun,” a Gilligan-obsessed ALF has a dream that he’s in the show and hobnobbing with Gilligan, the Skipper, the Professor, and Mary Ann. The Gilligan crew, meanwhile, reveal that they are superfans of a show that depicts the mundane life of the Tanners—ALF's adoptive Earth family. 

3. Alf and Mr. Robot

Hey, we said ALF gets around. In 2016, decades after his show’s cancellation, ALF came out of mothballs to make a cameo appearance in Mr. Robot. Paul and Linda Fusco, puppeteers for ALF in the original show (Paul did the voice), returned for Mr. Robot's second season episode "eps2.4_m4ster-s1ave.aes,” in which main character Elliot (Rami Malek) briefly finds himself inside a ‘90s-style sitcom.

In an interview with The Wall Street Journal, Mr. Robot writer/co-producer Adam Penn explained why ALF was the perfect choice for a cameo in the trippy techno-thriller about a man disconnected from reality: “While [ALF and Elliot] differ on a personality level, ALF was literally marooned on a planet away from home, isolated in a house, forced to try to fit in and connect with a family of strangers. There are certainly weird parallels between Elliot and ALF, which made the choice of our guest star seem like a no-brainer.”

4. Supernatural and Scooby-Doo

The recently-ended Supernatural was never a show to shy away from the weird and the meta; one season 6 episode sent main characters Sam and Dean Winchester into an alternate reality where—wait for it—their demon-hunting adventures are really a TV show, and they keep getting mistaken for the actors who play them. It wasn't too surprising, then, that Supernatural eventually got around to crossing over with monster hunting classic Scooby-Doo. In season 13 episode "ScoobyNatural," the Winchesters are sucked into an episode of Scooby-Doo by a cursed TV. The trio join forces with the Scooby Gang to fight a ghost—who actually is a ghost, not the Scooby-standard “human in a mask.” (The Winchesters telling the Scooby Gang that ghosts have been real the whole time causes them, of course, to have a mental breakdown.)

5. Roseanne and Absolutely Fabulous

In the infamous final season of Roseanne (at least until its 2018 revival), the working-class Conner family wins the lottery—at least it seems that way, until the final episode reveals that Roseanne made up her family’s unexpected windfall as a way to mentally cope with the death of her husband. In between the Conners winning the lottery and the explanation that they didn’t actually win the lottery, we got a Halloween episode (“Satan, Darling”) that doubled as a crossover with British sitcom Absolutely Fabulous. Jennifer Saunders (who also co-wrote the Roseanne episode) and Joanna Lumley appear as AbFab characters Edina and Patsy, who get drunk with Roseanne in New York City. Lumley later said of the experience: “It was very bizarre. We were quite confused. But it was fun."

6. I Love Lucy and Adventures of Superman

In I Love Lucy episode “Lucy and Superman,” Lucy and Ricky enlist Superman—played by George Reeves, star of ‘50s show Adventures of Superman—to put in an appearance at Little Ricky’s birthday party so that it won’t be overshadowed by a friend’s party taking place on the same day. Though it’s clear in the context of the show that “Superman” is actually Reeves dressed up as the superhero, the credits list him not as “George Reeves” but as “Superman”—meaning that, if you subscribe to the Westphall Theory of a Unified TV Universe, Superman and the entire DC universe take place in the mind of a kid from St. Elsewhere.

7. Boy Meets World and Sabrina the Teenage Witch

A crossover of Boy Meets World and Sabrina the Teenage Witch seems odd enough already, if only because Sabrina takes place in a world where magic exists, and Boy Meets World … doesn’t. But it gets weirder: In the season five episode "No Guts, No Cory," the core characters of Boy Meets World are transported back in time to World War II by Sabrina’s cat, Salem. Cory enlists and is almost killed in battle. He then comes down with a case of amnesia that makes him think he's a Frenchman. Sabrina star Melissa Joan Hart had appeared briefly in the previous season 5 episode "The Witches of Pennbrook," where she’s seen going on a date with Cory’s big brother Eric.

8. Power Rangers in Space and Ninja Turtles: The Next Mutation

The Teenage Mutant Ninja Turtles have gotten a lot of crossover action in comics, where Leonardo, Raphael, Donatello, and Michelangelo have hobnobbed with the likes of Batman, The X-Files’s Lone Gunmen, the Ghostbusters, and the cast of Archie. Talking TV, though, 1998 saw the Ninja Turtles—fresh from live-action show Ninja Turtles: The Next Mutation—pop over to Power Rangers in Space, the sixth season of the popular Power Rangers franchise. In the Power Rangers in Space episode “Shell Shocked,” the Ninja Turtles are brainwashed by the space witch Astronema into helping her steal the Power Rangers's spaceship. The turtles eventually break free of their brainwashing and team up with the Power Rangers to defeat Astronema and her minions in battle.

9. Doctor Who and EastEnders

British sci-fi institution Doctor Who has intersected a handful of times with British soap opera institution EastEnders. A two-part 1993 charity special called Dimensions in Time—which doubled as a thirtieth anniversary celebration for Doctor Who—sees the third through seventh incarnations of the Doctor attempt to stop the Rani from capturing a human, which would allow her to complete her quasi-zoo of all sentient lifeforms. The Doctor and various companions find themselves bopping through different time periods around London’s fictional Albert Square, where EastEnders take place; in the process, they meet several characters from the show. EastEnders has been referred to several times within Doctor Who as the fictional show that it is, making its actual appearance in Who canon a bit of a logical head-scratcher—nothing you wouldn’t expect from a show about traveling through space and time with an alien Time Lord in a police call box.

10. Batman and Hogan’s Heroes

A 30-second cameo raises some questions in the Adam West-starring Batman. The gag sees Batman and Robin, while climbing up a building, have a brief conversation with Colonel Klink from Hogan’s Heroes. Colonel Klink was the commandant of the POW camp that served as the main locale for the World War II-set sitcom Hogan's Heroes—so apparently this bona fide Nazi escaped to Gotham after the War, and Batman and Robin are content to just chat with him for a while without alerting the authorities? Questions, questions.

11. Archer and Bob’s Burgers

Archer and Bob’s Burgers are wildly different shows with a few key similarities. They’re both animated. They both exist under the Fox (now owned by Disney) television umbrella. And they both star the same actor: H. Jon Benjamin. So it made sense that there would be a crossover, even though Bob’s Burgers is family-friendly and Archer is decidedly not. The crossover took place in Archer’s fourth season premiere and sees special agent Sterling Archer (Benjamin) suffering from amnesia. Not remembering who he is, he's been living as Bob's Burger's titular patriarch Bob Belcher (also Benjamin) and running his restaurant with his family. Said family is drawn in the more realistic style of Archer, versus the more stylized look from Bob’s Burgers.