Different from the Class Reunion, the Reunion Show is an opportunity for the surviving cast of a defunct TV show — off the air for anywhere from 5 to 50 years — to get back together on screen. Usually this is an "in character" story showing how things are "now", but sometimes it can be an explicit reunion of the cast in tribute to the original show.
Unlike a Revival series (such as Still the Beaver and the at-one-time-endless progression of sequels to The Brady Bunch), the Reunion Show is a one-shot event. (Sometimes, though, reunions can spawn sequels.) Oddly, "in-character" comedy reunions tend to turn serious, if not outright dramatic, while most other shows are not altered.
Reunion shows are usually made to cash in on the nostalgia modern audiences can hold for an older program.
Typically done as a Made-for-TV Movie. Often accompanied by a Documentary with the actors out-of-character.
Much of the principal cast of Rave Master reprised their roles for the first time in 11 years in an OVA Cross Over with creator Hiro Mashima's later work, Fairy Tail. Mashima even treated the omake on which the OVA was based as a reunion for several characters in and of itself.
One of the earlier examples of this would be Father Knows Best, which had a pair of reunion movies in 1977.
Robert Young's other series, Marcus Welby M.D., also had two reunion movies, in 1984 and 1988.
Gilligan's Island had three of these in the late '70s and early '80s (Rescue from Gilligan's Island, The Castaways on Gilligan's Island and The Harlem Globetrotters on Gilligan's Island, respectively). The ratings success of the first one led to talk of a revival series, but Sherwood Schwartz (concerned with the aging cast doing weekly comedic stunts) preferred two additional movies instead.
The Mary Tyler Moore Show and The Dick Van Dyke Show have both had reunion TV movies since 2000. The former was a two-hour TV-Movie titled Mary & Rhoda and only featuring those characters. The latter was instead a single half-hour episode, but it reunited the surviving cast and featured clips of those that had passed on.
The Monkees had Hey, Hey, It’s the Monkees in 1997, which featured all four members in their wacky, not-yet-famous TV personas 30 years later, and was written and directed by Michael Nesmith. It was humorous in that their TV show which they “knew” they were on, had continued running, though not been aired, after all these years. The “plot” centered around finding a decent… well, “plot” to finish off the rest of the production money for the show (whilst preparing for a gig at “The Most Prestigious Country Club In the World”).
The Dukes of Hazzard reunion movie revolved around the wedding of Enos and Daisy Duke. A second reunion movie, Hazzard in Hollywood, came in 2000.
Yet another reunion show is coming for the show's 20th anniversary Super Megaforce, featuring ~10 of approximately 60 ranger actors—largely from older seasons—whom producers contacted by mass email a few weeks before shooting (out of many more who weren't contacted). That includes Jason David Frank, Sean Cw Johnson, Alison Mac Innis, Jason Faunt, Danny Slavin, Patricia Ja Lee and most of the rangers of Power Rangers Samurai.
Kaizoku Sentai Gokaiger is to Super Sentai as Kamen Rider Decade is to Kamen Rider. For the thirty-fifth anniversary the most notable ability of the Gokaigers is to transform into Rangers of previous years. However really ticking this box is the appearance of various characters from previous series as guest stars. Though most characters are replaced with Alternate Universe equivalents played by different actors, quite a few characters are played by their original actors.
In a rare case of a specific team coming back entirely on their own, Ninpuu Sentai Hurricaneger has a "Ten Years Later" V-Cinema special coming in 2013.
Like Super Sentai's "Vs." series, Kamen Rider recently started a series of movies of this nature, collectively known as Movie Wars. The most recent saw Kamen Rider Fourze, OOO, Double and the first seven Riders joining forces, though the focus was on the first two.
Green Acres had a reunion show in 1990 called "Return to Green Acres", which showed Oliver and Lisa still living on the farm. Most of the original cast was in it, but it was way too sappy and serious, especially when contrasted with the absurdist humor of the original series.
The Love Boat: A Valentine Voyage came several years after the show's end.
Ultraman Mebius and its tie-in movie Ultraman Mebius & the Ultra Brothers is this for the Ultra Series. And an example within an example which involves the class from Ultraman Eighty getting back together before their old school is closed down.
Seinfeld didn't have a real reunion show; however, in the series Curb Your Enthusiasm, where co-creator Larry David plays a fictionalized version of himself, there was a storyline in which he reunited the cast (who played themselves, and themselves playing the Seinfeld characters) for a reunion show.
I Dream of Jeannie: 15 Years Later (1985) had all the original cast save Larry Hagman, who couldn't participate due to his role on Dallas; instead, Wayne Rogers served as The Other Tony. A second reunion movie, I Still Dream of Jeannie (1991), kept Tony offscreen.
Friends has had numerous campaigns for a reunion Where Are They Now episode for the characters. The writers have had to put down several rumours and it's the number one question the actors face. And with the ten year anniversary of the finale coming up the pressure is only getting worse.
Drake & Josh's Christmas Special was made 18 months after the show ended. It may not seem like a long time, but because the show dealt with teenagers, it was obvious that they were too old for the show. Making it worse was that the movie was only supposed to take place a few weeks after the Grand Finale.
Mash had a 20th anniversary special in which the show's producers and surviving cast members gathered to reminisce.
'Allo 'Allo! did a reunion show in 2007 called The Return of 'Allo 'Allo!.
The 1957-66 Perry Mason television series had one, in the form of Perry Mason Returns (1985), featuring returning leads Raymond Burr and Barbara Hale. And another, in the form of Perry Mason: The Case of the Notorious Nun (1986). And another, in the form of Perry Mason: The Case of the Shooting Star (1986)... and a staggering 27 more Made For TV Movies made afterwards until 1995 (with Burr dying in 1993 and paving the way for several Suspiciously Similar Substitutes for the last four, with the umbrella title rechristened A Perry Mason Mystery).
The Six Million Dollar Man and The Bionic Woman had three reunion movies in the late '80s and early '90s; Return of the Six-Million-Dollar Man and the Bionic Woman, Bionic Showdown (which included some "Next Generation" bionic operatives) and Bionic Ever After, (in which Steve Austin and Jamie Sommers finally got married).
The XYZ Affair's video for the song "All My Friends" is an odd example, as it serves as a reunion more of a channel'sera than of a single show. Mike Marrona (Big Pete), Jason Zimbler (Ferguson) and Danny Cooksey (Budnick) team up with the XYZ Affair against Marc Summers, who here plays the band's irritated neighbor. Zimbler hits it off with a girl wearing a shirt reading "Ferguson is my Darling" and Summers ends the video by throwing green slime at everyone.
The Oprah Winfrey Show had a few of these in its final season, including one with Oprah's former competitors, Ricki Lake, Donahue, and Sally Jessy Raphael. She also reunited with Iyanla Vanzant, who she had a falling out with after she refused to do a Spin-Off show with Oprah and went to another network.
"A Reunion ...", the second-season premiere of Don't Trust the B---- in Apartment 23, deconstructed this trope. James van der Beek, who plays himself as a regular, regularly turns down his Dawson's Creek castmates' letters requesting a reunion. June, a fan when she was a teen, tries to suggest that he do it, and succeeds ... only for Chloe to let her know that she writes the letters, so James will feel powerful by rejecting them and thus she can get him to grant any wish of hers. June is undeterred, so Chloe drugs her and then spends six hours showing him DVDs of bad reunion shows from other shows (like The Facts of Life Goes to Paris) and reveals she's been the one writing the letters. James later reconsiders, but finds out from Busy Phillips that his former castmates all still hate him for not paying his share for a final gift to the crew, and won't say no outright but won't do it, either. Undeterred, he corners Frankie Muniz in the supermarket to pitch an idea for a combined reunion show, but Chloe again foils that. At the end, Mark-Paul Gosselaar appears to persuade James to live in the present, and they have a Viking Funeral for Dawson's Creek in the Central Park lake.
The 1981 musical Bring Back Birdie brought back the characters of Bye Bye Birdie two decades later. Chita Rivera was the only original cast member to reprise her role, though the original librettist and songwriters signed on.
One could say The Powerpuff Girls' 2009 special, Powerpuff Girls Rule, is a reunion of sorts as it includes virtually every main villain within the show and as well as brings back all the VAs who worked on the series.
Recess has the crossover special with Lilo & Stitch: The Series in 2005. By then, the show was over, and the cast was back to reprise their roles (except T.J., who had to be done by the same kid who did him in the DTV movies.