A guest appearance by someone with a personal or prior professional relationship with one of the cast members of the show, such as Rhea Perlman appearing on Becker, Christopher Lloyd appearing on Spin City, or Helen Hunt appearing on The Simpsons. More often than not the guest actor will be playing an Old Friend of the relevant character, whom they haven't seen in years.
Subtrope of Casting Gag. Liable to be a Large Ham. Expect numerous Actor Allusions. Compare Real-Life Relative. Not to be confused with Old Friend, Remember the New Guy? or Beleaguered Childhood Friend, but can overlap with any of them. Compare Relationship Voice Actor.
Live Action TV examples have their own page.
- Episodes 42 and 43 of the Angel Heart anime series involves Ryo Saeba (who is voiced by Akira Kamiya) dating a news reporter voiced by Yuriko Yamamoto. Kamiya and Yamamoto previously played Kenshiro and Yuria in the original 80's version of Hokuto no Ken.
- Spice and Wolf appears to do this in both Japanese and English. In the former, the two leads are played by Jun Fukuyama and Ami Koshimizu, who also played opposite each other as Lelouch and Kallen in Code Geass. In the latter, the leads are played by J. Michael Tatum and Brina Palencia, who also play the leads in Black Butler.
- All Christopher Guest films feature members of his Production Posse in different combinations, but it is particularly noticeable in A Mighty Wind; the Folksmen are played by the three main members of Spinal Tap. The video for a song from their 60s folk rock phase is clearly a Shout-Out to "Listen To The Flower People".
- Extreme example: In the Mystery Science Theater 3000-featured film Quest of the Delta Knights all sorts of hilariously awkward dialogue of this sort occurs between the Big Bad (David Warner) and The Mentor (David Warner).
- In Maverick (directed by Richard Donner), Bret Maverick (played by Mel Gibson) is in a bank that is held up by a gang, one of whom is played by Danny Glover (Gibson's co-star from the Lethal Weapon movies, also directed by Donner); the two men almost appear to recognise each other, but then dismiss the notion. (Then, to cement the association, as Glover's character is mounting his horse for a getaway he is heard to say, "I'm gettin' too old for this shit!" - Roger Murtaugh's famous catchphrase from Lethal Weapon.)
- In the epilogue of Harry Potter and the Deathly Hallows, Part 2, Draco Malfoy's wife is played by Tom Felton's real-life girlfriend.
- In The Senator Was Indiscreet, a William Powell vehicle, the final scene reveals that his wife, unseen till now, is Myrna Loy, who co-starred as his wife in numerous movies including The Thin Man series.
- Seeing James Spader as the main villain opposing a group led by Robert Downey, Jr. in Avengers: Age of Ultron is amusing, considering the two had previously worked together a few times in the 1980s. They actually played best friends in Tuff Turf, as well as slightly antagonistic associates in Less Than Zero.
- John Cho and Anton Yelchin, who played Sulu and Chekov in the Star Trek "Kelvin Timeline" films that started with the 2009 reboot, previously crossed paths before in the 2001 film Delivering Milo.
- Beauty and the Beast featured Jerry Orbach as Lumiere and Angela Lansbury as Mrs. Potts. They were very good friends, having worked together on Broadway and television. Notably, Orbach had a recurring role as hardboiled detective Harry McGraw in Landsbury's Murder, She Wrote.
- Catherine Tate and David Tennant of Doctor Who fame were reunited for an onstage production of William Shakespeare's Much Ado About Nothing. They are both prominently featured in its advertising. (The two are also close friends in real life.)
- Camelot was written and originally produced by much of the same team responsible for My Fair Lady (including director Moss Hart in the last Broadway show of his life). Not only did Julie Andrews have the starring role in both productions, but Robert Coote, who was Pickering in My Fair Lady, returned as Sir Pellinore in Camelot.
- Metal Gear Solid 4: Guns of the Patriots: In the Japanese dub, Snake is voiced by Akio Ohtsuka. When the older Big Boss, who Snake was cloned from, appears at the very end of the game, he was voiced by Akio's real-life father Chikao Ohtsuka.
- In the Mass Effect series Female Shepard and Ashley Williams are voiced by Jennifer Hale and Kimberly Brooks. The two have worked together as partners before... specifically band-mates Thorn and Luna from the various Scooby-Doo movies and shows. This makes it all the more funnier if you have a female Shepard and always include Ashley in your squad and then turn the Hex Girls song on while playing.
- One of the best moments of Shark Tale was when Robert De Niro said to Martin Scorsese, "We've worked together for a real long time."
- In the Batman: The Animated Series episode, "Beware the Grey Ghost", the Gray Ghost (a thinly veiled black and white Batman TV show copy) is voiced by Adam West.
- The Grey Ghost is also inspired by The Shadow, who himself inspired Batman.
- In Batman: The Brave and the Bold Blue Beetle's best friend Paco is played by Jason Marsden, who previously played Eric Matthews' best friend, er, Jason Marsden on Boy Meets World, and is Will Freidle's best friend in Real Life.
- This sort of thing happens a lot with these two.
- Also from Batman: The Brave and the Bold, Kevin Conroy, the voice of Batman from the 90s animated series, played the Phantom Stranger in "Chill of the Night!" alongside Mark Hamill, who famously played the Joker in that series, as the Spectre. The episode also featured Adam West as Thomas Wayne and Julie Newmar as Martha Wayne.
- The episode of The Batman that introduced Robin featured Kevin Conroy (Batman from B:TAS) as Dick Grayson's father and Mark Hamill (Joker from same) as Tony Zucco.
- When Pleakley's family comes to visit on Lilo & Stitch: The Series, they are voiced by many of Kevin MacDonald's former castmates from The Kids in the Hall. The only Kid in the Hall who didn't voice a family member voiced a preacher in that episode.
- In the sequels to Disney's Cinderella, Prince Charming is voiced by Christopher Barnes and Cinderella herself is now voiced by Jennifer Hale, AKA The Black Cat from the same series.
- Tara Strong and Cree Summer have been friends since childhood, even growing up together, and these days do a lot of voice-over work together. In other words, if you hear one of them in a given series, you're likely to hear at least one of the other two in the same series at some point.
- They've done enough shows together that their respective characters eventually parodied the infamous Sweeps Week Lesbian Kiss.
- A lot of cartoon voice actors (see Relationship Voice Actor) do this with people like Tara and Cree, as well as Grey DeLisle, Tom Kenny, Kevin Michael Richardson, Rob Paulsen, Carlos Alazraqui, the list could go on.
- In The Simpsons, Sideshow Bob is played by Kelsey Grammer. His brother and father are played by David Hyde Pierce and John Mahoney respectively, who played Frasier's brother and father.
- Brenda Song played a rival to Ashley Tisdale's Candace on Phineas and Ferb.
- One episode of Clifford the Big Red Dog had T-Bone (voiced by Kel Mitchell) meeting an old friend, Hamburger (Played by Kenan Thompson). If you're old enough, you'd remember that both of them starred together in two shows prior to breaking up due to creative differences.
- The Avengers: Earth's Mightiest Heroes!: David Kaufman showed up at the beginning of season 2 reprising his role of the Human Torch from past Marvel video games. Regular series heroine the Wasp is voiced by Colleen O'Shaughnessey, who voiced Danny's sister Jazz Fenton. Reportedly the two were excited to be working together again.
- In Avatar: The Last Airbender, Grey DeLisle voices Azula, and Mark Hamill voices her father, Fire Lord Ozai. In a third-season episode of Danny Phantom, the ghost of the week, Undergrowth, is voiced by Mark Hamill, and Sam Manson is voiced by Grey DeLisle. When Undergrowth takes control of Sam's mind, she even calls him "father".
- In The Mighty B!, Andy Richter voices Amy Poehler's little brother. On Late Night with Conan O'Brien, Poehler played Richter's little sister in a few sketches in the late 90s.
- In the Adventure Time episode "Everything's Jake", the character Jake is trapped in his own body and meets a guy called Goose. Although Jake has never seen Goose before, Goose claims that Jake is an old friend. This is because Goose's voice actor, Billy West, and Jake's voice actor, John DiMaggio, voiced the main characters Fry and Bender in Futurama.
- In Steven Universe, Greg Universe and his former manager, Marty, are voiced by Tom Scharpling and Jon Wurster of radio show-turned-podcast The Best Show. Compounding the Casting Gag is that despite the real-life duo being great friends and well-known comedy performers, Marty was such an utterly despicable black hole of a person (similar to awful characters Wurster used to play on WFMU, like the Gorch or Timmy von Trimble) and abused Greg so badly that Greg now considers him "dead to me", even though he was indirectly responsible for Greg meeting Rose.