Older Than Television: Winsor McCay's animated short, Gertie the Dinosaur, despite being one of the oldest animated films, successfully used this trope in live performances. McCay set up a projector on a vaudeville stage and interacted with the animated Gertie, commanding her to do tricks, tossing her a pumpkin (he palmed the real one while she caught an animated one), and ending the show by climbing into her mouth and being carried away. All this in 1914.
Another early proto-example is the Felix the Cat cartoon Felix Saves the Day. Some scenes use still photographs for Felix to interact with, and some live action film is cut in with the animation, but neither interact together at once.
Bob Clampett's Eatin' on the Cuff ends with a live-action narrator getting his pants eaten by a cartoon moth.
Zig-zag: The 1941 cartoon Porky's Pooch used live photographs as backgrounds.
The short "The Mouse That Jack Built" features an animated mouse version of Jack Benny running by his real life counterpart.
Done in Behind the Scenes segments of the original Woody Woodpecker Show. However, Woody is only shown animated against static photo backgrounds, and is never seen interacting with Lantz or anything else.
A good number of Cartoon Network interstitials feature characters from the channel's shows rubbing elbows with live actors, often in the CN office building.
[adult swim]'s "Checkered Past" block, which showcases early CN classics, recapture this vibe with their bumpers.
Hi Hi Puffy AmiYumi features an episode in which the live-action J-Pop stars sit on a couch with their animated manager, while the animated versions of the girls wonder who those two women are and who would want to watch them.
Miraculous Ladybug (a CGI-animated show) has the episode "Animaestro", with a titular villain who can change himself into 2D animated characters.
The revival The Fairly OddParents: Fairly Odder is in live-action, but has Cosmo and Wanda depicted in traditional two-dimensional animation.
Infrequently done for comic effect on SpongeBob SquarePants when the characters go on land. In one episode, they were all portrayed as crude puppets. In The SpongeBob SquarePants Movie, part of the climax even involves SpongeBob and Patrick receiving help from an Adam WestingDavid Hasselhoff. Recently, in the 20th anniversary special, Spongebob and Patrick travel on land for a sight-seeing tour.
During the first year of Kids' WB!, the stars of the sitcoms on The WB appeared in promotional spots and bumpers depicting them hanging out at the animated version of the Warner Bros. studio lot (as seen on Animaniacs).
TV of Tomorrow has live action for all the televised images.
Who Killed Who? starts with an onscreen presenter introducing a murder mystery, and in the end the murderer is unmasked and revealed to be the very same presenter.
Señor Droopy ends with Droopy sitting on the lap of '50s actress Lina Romay.
The Peanuts special It's the Girl in the Red Truck, Charlie Brown has Snoopy's brother Spike becoming infatuated with the live-action title character (played by Charles Schulz's daughter, Jill).
The Disney Channel's music video of "It's On", made to promote the Camp Rock 2 movie, in which Phineas and Ferb are periodically depicted dancing with real people who were hired to lipsync to the song.
The spin-off Take Two with Phineas and Ferb has the title characters hosting a talk show where they interview real-world celebrities.
The Powerpuff Girls (1998) did this with a music video for Apples in Stereo's "Signal in the Sky (Let's Go!)". It was shot on a miniature live-action set to resemble Townsville, with the Giant Fishballoon played by someone in a costume and wrecking the set apart. The live action citizens and the band were chroma-keyed into the set, as well as the scene where the monster rises out of the water, and the animated Powerpuff Girls were reused from specific episodes of the show.
"Homer³", one of the Three Shorts of "Treehouse of Horror VI" , ends with 3D Homer being transported into the real world (if you can call Los Angeles real). If you pay attention to the people around him, they seem very well aware that the strange, yellow man walking down the sidewalk isn't normal. None of them seem to do anything more than stare, however, and Homer freaking out over being in the real world is cut short when he goes inside an erotic bakery.
Also "Treehouse of Horror IX", "The Terror of Tiny Toon", has Bart and Lisa trapped inside a TV with Itchy and Scratchy trying to murder them. At one point Homer changes the channel and they end up ruining a scene for Regis and Kathy Lee (it was originally going to be the FOX legal dramedy Ally McBeal, but Calista Flockhart (the show's star) declined. It does explain why a morning show like Regis and Kathy Lee would air at night).
In March of 1959 Cambria Productions came up with the show Clutch Cargo, which used the then cutting-edge idea of combining animated characters with live-action mouths superimposed onto their faces, called "Synchro-Vox", this show had the distinction of horrifying its target audience and inducing more childhood nightmares than H. R. Giger could ever dream of. Cambria struck again a year later with Scott McCloud: Space Angel and also prepared a pilot based on the comic strip Moon Mullins (which did not get optioned as a series). Both used the Synchro-Vox technique.
South Park has a two-parter ("Pandemic") featuring giant, real-life guinea pigs "rampaging" through town.
In a truly bizarre example of this trope, in the late '40s, when Columbia Pictures was making live action Superman serials, in order to save money on the flight effect, they actually had Superman turn into a cartoon version of himself when he flew!
One segment of "Road to Rupert" was nothing but the scene in Anchors Aweigh (see "Films" above) with Stewie drawn over Jerry.
In "Brian's Got a Brand New Bag", Brian mentions to Rita that he had a bit part in Die Hard. It then shows actual footage from the movie with an animated Brian inserted into the clip.
The whole premise of Space Ghost Coast to Coast is an animated talk show where Space Ghost would interview live-action people via TV screen.
Archie's Fun House shows Archie and friends performing for a live-action audience of children.
Similar to the Archie example, the Animaniacs episode "You Risk You Life" had Yakko doing a game show in front of live action people.
Sit Down, Shut Up zigzags this trope. The backgrounds are live photographs, but the characters are animated.
A sketch that parodies the Boglins have the creatures themselves as live-action puppets, but the rest of the characters are stop-motion as usual.
The opening to NBC's The Pink Panther Show opens with a live-action opening where a kid driving a "Panthermobile" drops the Pink Panther and The Inspector off at Grauman's Chinese Theater. The credits show the Inspector going in and the car driving away, leaving the Panther to chase after it.
At one point in Clone High's Mushroom Samba episode, Gandhi is miniaturized and eaten by a (live action) housecat.
The Amazing World of Gumball has static, heavily-edited photographs for backgrounds and characters that are animated in 2D, CGI, and one character and her family is a live-action puppet (specifically a live-action actor's upside-down chin). However, the live-action actors only appear on in-universe videos and TV shows, never together with animated people, until the Series Finale has a live-action human (seemingly) as the antagonist.
A Fat Albert and the Cosby Kids television special made before the Saturday morning series was done in a much more realistic, sketchy character style against live-action backdrops.
Zig-zagged in the The Beatles episode "Paperback Writer". The cartoon Beatles are seen in concert with photos of their real-life counterparts in the background.
In 1968, Hanna-Barbera had The New Adventures of Huck Finn, which had Mark Twain's titular boy protagonist along with Becky Thatcher and Tom Sawyer, all live-action youths, amidst cartoon backgrounds and figures.
The Alan segments in Modern Toss feature the titular character, a sort of animated scribble with a face, playing very cruel tricks on his live-action co-stars.
The obscure Game ShowSkatoony features live-action children competing against toons on an animated quiz show.
The earliest Terrytoons from 1930 opened with a silhouetted live-action orchestra performing over an animated background.
The 1991 short Manipulation, inspired by the classic Duck Amuck, features the hands of an animator, shown in live-action, manipulating a cartoon man. At the end of the cartoon the animator throws the drawing in the garbage, only for the cartoon man to crawl out of the garbage can.
The 1984 National Film Board of Canada short Real Inside satirizes hiring practices by having an animated dog named Buck Boom going for a job interview at an accounting firm.
Blue's Clues: Steve is a real human Excited Kids' Show Host who interacts with the green screen animated world around him. All the other characters are animated.
The Scooby-Doo Project had the Scooby-Doo gang interacting in the real world. Shaggy hangs a lampshade on this by pointing out that the woods look more realistic.
Muppet Babies (1984) uses footage of live-action movies as a general rule, but in one episode in particular, "The Incredible Shrinking Weirdo", there is a scene where a live-action adult Kermit interacts with an animated Baby Gonzo. A clip from The Muppet Show (Episode 223: John Cleese) was used, with Frank Welker (the voice of Baby Kermit) dubbing new lines for Kermit and with Baby Gonzo matted into the scene.
Other episodes saw the babies interacting with celebrities like Stan Lee and Whoopi Goldberg.
Muppet Babies (2018) doesn't do this as often as the 1984 series, but it pops up now and then. "Animal And The Egg" has Animal and Summer try to take care of a baby egg while everyone else looks for the mother. The Muppet Babies, who are CGI, are shown interacting with real life birds.
In the Daniel Tiger's Neighborhood book The Helpers in Your Neighborhood (based on an episode that has yet to be released), Daniel Tiger and Dad Tiger venture out of the Neighborhood of Make Believe and meet various real-world helpers, including a construction worker, a mailman and a police officer. They are shown interacting with these people in this manner.note Although this is a book, we'll list it here, since it uses stills from the television series and is an adaptation of an episode, albeit one not yet released.
This is used in the Internet-only short "Where Did I Come From?" from Sid the Science Kid' to depict Sid meeting the folks involved in the show's production and getting at the technical processes which created him and the show.
The music video release of the theme song of Stanley, "My Man Stanley," uses this to insert Stanley, Harry, Elsie and scenes from the show into a scene of the Baha Men performing at a beach.
Pibby: As well as going through a number of animated series while fighting the Static, the main trio also stumble upon a live-action advertisement at one point, where a child appears to be shocked by their presence.
PBS has made a series of shorts based on Elinor Wonders Why called "That's So Interesting", where Elinor and her friends, still in cartoon form, interact with Jorge Cham (their creator) in real life and talk about science. Bonus points for Elinor, as well as being a rabbit, having the same surname as Roger; you could call this the Elinor Rabbit Effect.
The Fanboy and Chum Chum episode "Slime Day" has Fanboy and Chum Chum go to Nickelodeon headquarters to try and learn the secret word for Slime Day that way. The scene has CGI-animated Fanboy and Chum Chum interacting with Don Newhouse and the president of Nickelodeon in live-action.
, made to promote the Camp Rock 2 movie, in which Phineas and Ferb are periodically depicted dancing with real people who were hired to lipsync to the song.