The 20 most memorable crossover TV episodes

Two of Shondaland's most powerful women, Olivia Pope and Annalise Keating, finally came face-to-face in this epic two-part event. Watching these titans team up to take a case to the Supreme Court was the crossover fans had been dreaming of for years.

This crossover was the absolute pinnacle of Disney Channel television. It was a three-part special that saw three of the network's biggest shows collide. From Raven's stay at the Tipton to Hannah Montana's run-in with Maddie, it felt like a pop culture supernova.

In one of the most creative crossovers of all time, Sam, Dean, and Castiel were literally zapped into an episode of the classic cartoon Scooby-Doo. The episode, aptly titled "Scoobynatural," was a hilarious and brilliant love letter to both shows.

The "Crisis on Infinite Earths" event wasn't just a crossover; it was a universe-shattering showdown that brought together nearly every DC TV show imaginable. Seeing characters from Smallville and even classic DC movies appear was pure fan service of the highest order.

After years of cheeky rivalries, the Griffins took a road trip and ended up in Springfield for a full, hour-long episode of TV greatness. The crossover was packed with hilarious jokes and an instantly legendary fistfight between Homer and Peter.

These two shows were famous for their emotionally devastating crossovers, often featuring characters popping up in the other city for a crucial mission or a heartbreaking conversation. Fan favorites like Buffy, Willow, and Spike all made memorable trips from Sunnydale to Los Angeles.

The nerdy neighbor Steve Urkel from Family Matters and his malfunctioning jetpack accidentally crashed in the Tanners' backyard. This episode was a huge event that also saw Urkel giving Stephanie advice on getting glasses.

When Jess and her loft-mates visited New York, they crossed paths with Jake Peralta, who commandeered her mom's car for a case. It was a charmingly goofy and low-stakes crossover that perfectly blended the two shows' quirky comedic styles.

In one of the most bizarre and wonderful pairings ever, the scientific world of Bones collided with the supernatural universe of Sleepy Hollow for an extra spooky Halloween special. 

When Dr. Addison Montgomery left Seattle Grace for sunny Los Angeles, it kicked off years of crossovers between the two medical dramas. Characters frequently traveled between the two hospitals for tough cases, creating a truly connected Shondaland universe. 

The first family of the future met the first family of the past in a feature-length animated special. A failed time machine experiment sends the Jetsons back to the Stone Age town of Bedrock, resulting in pure cartoon chaos.

In a clever bit of world-building, Lisa Kudrow's Phoebe Buffay was established as the identical twin sister of Ursula Buffay, a waitress on Mad About You. Ursula would occasionally pop up on Friends, much to Phoebe's annoyance.

The detectives of the Special Victims Unit have crossed paths with many other shows, but their cases with the Chicago Intelligence Unit are always a highlight. Seeing Olivia Benson team up with Hank Voight combines the best of two gritty Dick Wolf franchises.

This was a massive television event for Nickelodeon fans, as a teleporter mishap sent Timmy Turner to Retroville and Jimmy Neutron to Dimmsdale. The TV special also blended 2D and 3D animation as the two kid geniuses had to work to fix each other's worlds.

The firefighters of Station 19 and the doctors at Grey Sloan Memorial exist in a tightly woven universe of shared crises. Hardly an episode goes by without a character from one show making a crucial appearance in the other, especially during the massive city-wide emergencies.

In a moving crossover event, Dr. Susan Lewis from ER traveled to New York City to search for her missing sister. The search led her to the first responders of Third Watch, who helped her navigate the city during her crisis.

The iCarly and Victorious crossover event was the Nickelodeon special every kid was waiting for in 2011. The plot involved Carly dating a boy who was secretly cheating on her with Tori Vega, leading to a massive party and a truly iconic musical performance.

This entire series served as a crossover, bringing together the tough-as-nails Sam Puckett from iCarly and the sweet, ditzy Cat Valentine from Victorious, and making them roommates. The show was built on the hilarious chaos that ensued when these two polar-opposite fan favorites started a babysitting business together.

Two of CBS's biggest action-procedural teams collided for a massive two-night event, joining forces to stop a deadly virus. Talk about explosive drama!

In another classic TGIF crossover, Steve Urkel's invention mishap lands him in the Foster-Lambert family's backyard in Port Washington, Wisconsin. He ends up helping Mark Foster with his science fair project and, of course, annoying the rest of the blended family with his clumsy antics.