Darrin, obviously. Dick York had to be replaced after five seasons because of a past disabling back injury that had torn the muscles on the right side of his back, and developing a strong addiction to pain killers. During his final season on Bewitched, entire episodes had him sitting on a couch or lying in bed. Things were already tensing up as he struggled to remember his lines and show up for work, and execs wanted him fired almost from the beginning, but the final blow was a seizure he had on set that caused him to fall off a platform and bite a hole into his tongue, and it was mutually agreed upon that it was time to go. York would go on to spend years bed-ridden and fighting to overcome both his injury and an addiction to pain killers (which he did). The change to Dick Sargent (who ironically was originally offered the part in the beginning, but was unavailable at the time) was very quiet, but audiences were quick to notice "something different" about Darrin. To this day, it is extremely unusual for an actor playing a main character in a television series to be abruptly replaced like this. This example might even be the reason why. History repeated itself 15 years later when the actor who played the father on another supernatural sitcom, the 1980s obscurity Down to Earth, was replaced. The replacement: Dick Sargent!
Gladys Kravitz was originally played by Alice Pearce. When she died of ovarian cancer in the middle of the second season, Sandra Gould replaced her in Season 3 (For the end of Season 2, Abner's sister, Harriet Kravitz, played by Mary Grace Canfield, "filled in" for Gladys).
Louise Tate (Larry's wife) was first played by Irene Vernon, later by Kasey Rogers. This was allegedly due to politics, as Vernon was good friends with writer Danny Arnold, who got into a spat with execs, causing them to fire him. Those execs also made sure Vernon was gone as well. It was possibly mutual though as Vernon's husband was ill at the time, and she wanted to spend more time taking care of him. Vernon never acted in film or television again.
Frank Stephens, Darrin's father; first played by Robert F. Simon, later by Roy Roberts (with an occasional reprise by Simon). In fact, the changes to Gladys Kravitz, Louise Tate and Frank Stephens, as well as Erin Murphy assuming the role of Tabitha, all occurred between the second and third seasons, when the show switched from black-and-white to color, only compounding the show's different look and feel.
The Ur-Example is The Goldbergs (not to be confused with the unrelated ongoing series of the same name). The television version ran on CBS Television from 1949 to 1951 and co-starred Philip Loeb as Jake Goldberg. In 1950, Philip Loeb was blacklisted and accused of being a Communist, and pressure was placed on Gertude Berg (who both starred in and owned the television version as she had the radio original) to fire him. When she refused, General Foods cancelled their sponsorship, and CBS dropped it from their schedule by June 1951. Eight months later, however NBC the show's original broadcasting home picked up the series for the 1952-53 season, but informed Gertrude Berg that if she persisted in allowing Philip Loeb to remain with the series, it would never be seen on television again. She finally gave in, and the series reappeared in a twice-weekly, early-evening 15 minute format (with another change in title, to Molly, in due course), with Harold Stone and then Robert H. Harris replacing Loeb as Jake, though Berg quietly continued to pay a salary to Loeb.
Mad About You played this trope straight, then subverted it, in the form of Paul and Jamie's neighbors Maggie and Hal Conway. Paxton Whitehead originated the role of husband Hal Conway and played it for a few episodes. When he wasn't available for an episode, actor Jim Piddock took over the role, implicitly playing the same Hal. Much later, Whitehead was available again. In the first episode upon his return Maggie says, "I divorced my second Hal, and remarried the first one."
The trope was played completely straight with Jamie's parents, who are played by three sets of actors, culminating in the Stunt Casting of Carol Burnett and Carroll O'Connor.
Roseanne had lots of fun with this trope when Sarah Chalke replaced Lecy Goranson as the Conners' eldest daughter Becky for three seasons. She originally took over for Season 6 when Lecy Goranson chose to focus on school, however Goranson returned for Season 8 when her schedule worked out (with Chalke still filling in three episodes when Goranson was unavailable), but Chalke once again took over full-time for Season 9 after Goranson quit for good. The scriptwriters brazenly point it out at several points.
When the new Becky angers Roseanne in one episode, Roseanne quips, "I can have you replaced, you know."
The very first time the original Becky appears onscreen upon returning this conversation ensues between her and Roseanne.
Becky:(carrying paint rags) Here, dad this is all I could find. Roseanne: Where in the hell have you been? Becky: Don't yell at me mother, I was getting this. Roseanne: Well it took you long enough seems you've been gone for three years.
Darlene's first words to the character are "Where the hell have you been?". Which she replies by asking "why does everyone keep saying that to me?" during which the actress is barely holding back laughter.
In one episode, both actresses appeared, recreating the opening sequence from The Patty Duke Show (although some thought it was the Marx Brothers' famous "mirror gag"). The second Becky appears at the Conner's doorstep with a pair of trick or treaters and cheerful attitude, Mark (the character's husband) remarks "this is like déjà vu all over again" and Roseanne later comments "Gee, I wish we had a daughter that sweet."
Chalke was introduced by the cast specifically referencing this trope in The Tag of her first episode, the family is watching Bewitched and the topic of how an actor change should be presented to the viewing audience is brought up, right before the camera focuses on the new Becky for the first time. She then smilingly comments that she prefers the second Darrin.
Also, in the Disney vacation episode, the Becky actresses changed AGAIN for that one episode (along with two other season 8 episodes), and when the actress first entered the episode it paused, a voiceover explained the full history of the two actresses switching, and later Roseanne comments "Aren't you happy you were here today?"
Also, a Clip Show with a framing sequence set in the future featured John Goodman as an adult DJ, almost catatonic following some mysterious trauma in his childhood. He just kept repeating "They say she's the same, but she isn't the same."
...and Becky wasn't even the only Conner child to be replaced. Sal Barone, who played DJ only in the pilot, was replaced for the series by Michael Fishman.
In a take similar to Roseanne, the characters in Bette Midler's sitcom Bette were discussing this trope around the breakfast table. In episode 13, Bette says something like "Don't you hate that, Roy?" Roy looks up from behind the fridge door, and we see that he's now played by Robert Hays instead of Kevin Dunn.
Also Lindsay Lohan played Rose in the pilot, with Marina Malota in the rest of the series. The pilot was taped in New York, but when production moved to Los Angeles for the main series, Lohan wasn't willing to commute or relocate, and her role was recast. However, producers opted not to reshoot the pilot (in part due to Lohan's newfound star power at the time), leading to this trope.
In the second episode of Friends, Ross's ex-wife Carol was played by Anita Barone, whose look and acting style were nothing like those of Jane Sibbett, who replaced her for the rest of the series.
Also Rachel's friend Mindy, who eventually married her ex-fiancé, was originally played by Jennifer Grey.
Happens to Ben and Emma too, but it's less noticeable since they were both babies when this happened.
A year later, Barone played a major role on The Jeff Foxworthy Show for an entire season, then Ann Cusack replaced her.
Don Draper's son Bobby on Mad Men. As of the 5th season, the new actor will be the Other Other Other Darrin.
The 1980's British sitcom Bread replaced actors for three of its major characters. Julie (Billy's girlfriend) was played by Caroline Milmoe for the first two seasons and Hilary Crowson from season 3 to 5. Joey was played by Peter Howitt from season 1 to 5 and Graham Bickley thereafter. Aveline was played by Gilly Corman from season 1 to 4 and Melanie Hill thereafter.
Degrassi Junior High quietly got rid of a wheelchair bound actress and replaced her with another girl in a wheelchair, most likely when the producers decided to actually make her into a significant character. The Agony Booth recap of a first season episode acknowledges this, along with the trope namer, referring to the first actress as "the Dick York of Wheelchair Girls."
The character of Elizabeth Weir was introduced in the two-part seventh season finale of Stargate SG-1, played by Jessica Steen. When she reappeared in the first two episodes of Season 8, and then as the lead in the spin-off Stargate Atlantis, she was played by Torri Higginson. Jessica Steen was reportedly rather disappointed that she wasn't even asked to reprise the role. This was a rather jarring replacement, as Jessica Steen (at the time) was blonde, and Torri Higginson is a rather dark brunette. A case where they didn't bother to at at least cast a similar looking actress.
For the character's final, send-off episode, Weir was played by yet another actress, Michelle Morgan (with a fourth actress portraying her in flashbacks!), although the switch was justified in-plot by stating that Weir had downloaded her consciousness into a series of android bodies after her original body was destroyed by the Replicators.
Also, the character of Cassandra was originally played by Katie Stuart in "Singularity" but was later played by Colleen Rennison in "Rite of Passage"... because Katie Stuart was busy being the Other Kitty Pryde in X2.
The humanesque wraith Michael was played by Connor Trinneer in all but one appearance, where he was played by Brent Stait. Connor did, however, still provide the character's voice.
The first time we meet Teal'c's wife, Drey'auc, she is played by Salli Richardson. Subsequent appearances would be by Brook Parker.
Ben, the older of the two Hartman brothers on Hearts Afire, was recast in the show's third season. He changed from a stocky blonde to a skinny brunette and didn't bear any resemblance whatsoever to his previous actor or his character's brother.
In a first-season episode of The Facts of Life, Blair's mother, Monica Warner, was played by a voluptuous early-30s blonde actress (Pam Huntington) in what was apparently a one-shot appearance. However, several seasons later, Blair's mother became a Recurring Character, and she was played by svelte 40-something brunette Marj Dusay.
Sabrina's father is played by Robbie Benson in the first season. He does not appear again until Season 4, where he's now played by Doug Sheehan.
Pamela Blair played Sabrina's mother Diana in Season 2. For her Season 6 and 7 appearances, she's played by Alley Mills.
Cousin Marigold was played by Robin Ricker in Season 1 and Hallie Todd in Season 3.
On The Golden Girls, different actresses played visiting children quite a lot. Rose's daughter Kirsten was first played by Christina Belford in her initial appearance, then later played by Lee Garlington. Dorothy's daughter Kate was first played by Lisa Jane Persky, then by Deena Freeman. Dorothy's sister Gloria was first played by Doris Belack, then by Dena Dietrich. The most drastic difference was Blanche's daughter, who was played by a heavy actress in her first appearance, then by a much slimmer, more attractive actress in her second appearance.
On The Partridge Family, the first Chris, Jeremy Gelbwaks, was fired at the end of the first season (reportedly for starting fights with other cast members) and replaced by Brian Forster, who looked absolutely nothing like him.
Actress Caitlin Brown played the Narn attache Na'Toth in the first season. Brown then quit due to trouble with her prosthetic makeup and also in order to expand her film career she was replaced by Mary Kay Adams. In one episode of the final season, Na'Toth reappeared alive after being presumed dead, in a Centauri prison cell Caitlin Brown came back for this final appearance of the character.
Also, the first actor to play the recurring role of Draal was unavailable after one episode, so a younger actor was selected with a Lampshade Hanging that the machine he was plugged into in his last appearance not only extended his life but restored his youth. Later the second actor left for Broadway, and the character was dropped entirely as everyone agreed it would be too much to expect audiences to accept a third actor. To further complicate matters, the original actor later returned portraying a different recurring character, Brother Theo.
Sheridan's wife Anna was originally portrayed in photos, video clips and flashbacks by Beth Toussaint, who looked nothing like Melissa Gilbert, brought in when Anna became a "live" on-screen character after her "resurrection". At the time of her casting, producer J. Michael Straczynski considered re-editing earlier episodes to replace the original actress with Melissa Gilbert but decided against it.
On Lois and Clark, the character of Jimmy Olsen was played by Michael Landes in Season 1, but was then replaced by Justin Whalin in Season 2. The showrunners were worried that Landes looked too much like Dean Cain and played Jimmy is too "slick" rather than the slightly geeky character they wanted.
Lois And Clark also had the distinction of recasting Lois' entire immediate family. Lois's father was initially played by Denis Arndt, providing a bland Sam Lane in the character's Season 1 introduction, and Harve Presnell as a more caustic version in a string of appearances starting in Season 3. Her sister, Lucy, was initially portrayed by Elizabeth Barondess in the show's first three episodes before disappearing; when she returned, she was played by Roxana Zal. Lois's mother was played by Phyllis Coates during the first season finale, and in subsequent appearances by Beverly Garland. Coates' appearance on Lois and Clark also qualified as Stunt Casting, as she played Lois Lane in the feature film "Superman and the Mole Men" and later in the classic The Adventures of Superman TV show (where, ironically, she was replaced after one season by Noel Neill, who had previously played Lois in Superman's first live-action screen appearances, the 1948 and 1950 serials starring Kirk Alyn making Neill her own Other Darrin's Other Darrin).
Clark's biological father, Jor-El, was played by three different actors: David Warner in season 1's "Foundling", an unknown in season 3's "Never on Sunday" and François Giroday in the season 3 finale "Big Girls Don't Cry". All portrayals were flashbacks or recordings from when Clark was a baby on Krypton, so the three actors were portraying the same character within a relatively short timeframe.
Lois and Clark featured several appearances by a time-traveling H.G. Wells (an idea that probably deserves its own trope page), but due to actor availability issues, his appearances alternated between an older Wells played by Hamilton Camp and a younger one played by Terry Kiser.
Also happened on another Superman show, The Adventures of Superboy, except this time, it was the title character. Superboy actor John Haymes Newton supposedly demanded a higher salary and/or was convicted of a DUI after the first season of the show, so he was replaced with Gerard Christopher for Season 2. The same thing happened with the role of Lex Luthor, which passed from Season 1's Scott Wells to Sherman Howard for the remainder of the show.
Strangest example ever: the two Gabys from Ghostwriter. Gaby started out as Alex's pesky little sister, until the actress hit her growth spurt and was as tall as Alex. So later scripts changed Gaby's personality to reflect this. Then the actress was replaced by a new, shorter one and Gaby reverted to her old personality.
Though Doctor Who is famous for its use of The Nth Doctor and tends to provide an in-story reason for the changed actors, there were a few characters that had Other Darrins:
For "The Five Doctors", which featured the first five Doctors (albeit one in unused archive footage), William Hartnell, the actor who originally played the First Doctor, had since passed away, so Richard Hurndall stepped into the part. In "The Day of the Doctor", the First Doctor appears courtesy of archive footage with a new voice clip provided by impressionist John Guilor.
Colin Baker, the Sixth Doctor, was notable for having been fired from the job. Since Colin wasn't willing to return only for a regeneration scene, the next season began with Sylvester McCoy laying down on the ground, in Sixth Doctor costume and a wig, until the regeneration into the Seventh incarnation moments after the beginning of the episode. (Given the circumstances, this would count as a Bridge Drop, too.)
Davros, creator of the Daleks, was played by Michael Wisher in Season 12, then in his next appearance in Season 17 by David Gooderson, then throughout the 80s and later in the Big Finish Doctor Who and I, Davros audios by Terry Molloy. In the 21st-century revived series, he is played by Julian Bleach. While the heavy mask prosthetics makes it hard to tell (aside from the mask made for Wisher fitting horribly on Gooderson), their voices do all differ from each other, despite Sarah Jane recognising the voice of Bleach's Davros on a radio message after only meeting Wisher's.
Peter Pratt and Geoffrey Beevers played the same incarnation of the Master in different stories. As with Davros, the heavy makeup may have made it hard to tell. According to the Doctor Who Expanded Universe, this is supposed to be a heavily decayed version of (sans heavy makeup) Roger Delgado's incarnation, who was a semi-regular from 1971-73. There is also another incarnation of the Master shown during his execution at the beginning of the TV Movie it's kept purposefully ambiguous, but the assumption is that it's the Ainley incarnation of the Master, played briefly by a different actor.
In the Second Doctor story The Macra Terror, Chicki was played by different actresses in Part 1 and Part 4.
K9, normally voiced by John Leeson, was voiced by David Brierly for Season 17 because John quit. Fortunately he came back for Season 18 and all of K9's subsequent return bus trips.
Game On replaced the actor playing Matt, Ben Chaplin, with Neil Stuke, and concluded Stuke's first episode with the characters watching Roseanne commenting how much they hated it when a show switched actors. (Almost certainly a Shout-Out to Roseanne doing a Shout-Out in The Other Becky's first episode, with Bewitched.)
GOB's girlfriend Marta on Arrested Development was played by three different actresses during the series' run. This is pointed out in the DVD commentaries. George Michael's girlfriend Ann was also played by a different actress in her first appearance. Word of God is that they planned to cast a new actress for Ann Veal for each appearance; this was abandoned but the "Her?" Running Gag remained.
Bobby's dead wife in Supernatural, whose original actress from the third season episode "Dream A Little Dream of Me" was pregnant at the time of her reappearance in Season 5. The producers seemed uncomfortable with the idea of a pregnant zombie wife.
On Titus, Titus's violent, manic-depressive schizophrenic mother Juanita was played by three different actresses. In season one's "Mom's Not Nuts," Juanita was played by Christine Estebrook. In season two's "Locking Up Mom," "The Reconciliation," and "The Wedding," Juanita was played by Frances Fisher. In season three's "The Trial" and "The Visit," Juanita was played by Connie Stevens note It should be noted that Christine Estebrook had Juanita as a brunette, while Fisher and Stevens had Juanita as a redhead. Whether this reflected Juanita's mental illness or was merely an oversight in casting is not known.
Krista Errickson replaced Donna Wilkes as Diane Alder after the first season of Hello Larry.
In the Disney series Flash Forward (1996), Becca's sister Ellen was played by Rachel Blanchard for the first four episodes and Robin Brule for the rest of the series. It should be noted, however, that the amount of real-world time between episodes four and five allowed Jewel Staite to film the entire first season of Space Cases.
Robin Hood was played by Tom Ellis in his first episode, and by Sean Maguire when the character became a series regular. A later backstory episode showed Robin acquiring a pendant that could disguise oneself which many interpreted to be a nod to Robin looking different in his first appearance.
Actually subverted with Ursula the sea witch. In her first appearance, she was voiced by Yvette Nicole Brown. Ursula physically appeared the next season played by Merrin Dungey. But a few episodes later it's stated that Dungey's Ursula is actually named after Brown's (Brown's being an ancient sea goddess and Dungey's named in her honour).
In the spin-off Once Upon a Time in Wonderland, the character of Jafar debuted, played by Naveen Andrews. When Jafar made it onto the main show a few years later, Naveen Andrews was too busy to reprise his role, and Oded Fehr was cast in the part instead.
Played with in Due South, when Callum Keith Rennie was brought on to replace David Marciano, the original Ray Vecchio: Rennie appeared in the switchover episode as "Vecchio", who turns out in fact to be an entirely new character, Ray Kowalski, imported by the FBI to impersonate Vecchio while he went undercover with the Mob despite looking nothing like Vecchio. Benton Fraser, the main character, spends most of the episode being the Only Sane Man, who alone appears to have noticed the change as the supporting cast all insist that this is indeed Vecchio, before finally getting round to putting him in the picture. (Both Rays put in an appearance in the series finale.)
But played straight with Fraser's deaf half-wolf Diefenbaker: played in the Pilot Movie by Newman, the first & second seasons by Lincoln, and Draco in the third.
Bonnie Dennison took over the role of Emily Yokas for Third Watch's fourth season, as the character became more involved in the storylines. This caused many characters to question when Emily "became so grown up".
On Profiler, Sam Waters' daughter, Chloe, played for two seasons by the prepubescent Caitlin Wachs, suddenly turned into the obviously adolescent Evan Rachel Wood in Season 3. Thus, a character who within the show's time frame was sleeping with stuffed animals and being read bedtime stories a week ago became concerned with boys and make-up almost literally overnight. Kids grow up so fast, don't they?
Vice-president's brother and living supposed murder victim Terence Steadman from Prison Break was first played by John Billingsley, and then Jeff Perry, due to Billingsley becoming a regular on another show. Ironically, he's kidnapped by the main characters who argue over whether he'll be seen as just a imposter.
Seinfeld handled this interestingly. The first time George's father appeared, he was played by John Randolph, who was replaced by Jerry Stiller for all later appearances. The scenes with John Randolph were actually re-shot with Jerry Stiller playing the part, and the re-shot scenes were what was shown in reruns.
Similarly, the character of Newman made his debut with a voice-only appearance (played by creator Larry David) in Season 2's "The Revenge". After Wayne Knight assumed the role on-screen, Newman's lines in "The Revenge" were rerecorded with Knight's voice.
Jerry's father was played by Phil Bruns in his first appearance and Barney Martin subsequently; the producers had wanted to reshoot with Barney Martin too, but found that the other actors had aged too much since the first season for the replacement to be convincing.
The character of Lloyd Braun was played by Peter Keleghan in his first appearance and Matt McCoy in subsequent appearances. The two actors look nothing alike.
In Curb Your Enthusiasm, Larry David makes a Seinfeld reunion. When Jason Alexander quits, Larry suggests that he will play George instead, and brings up the other Darrin as an example.
The meta-humor here is that "George" was originally created a stand-in for Larry David's personality; David did not feel confident acting in a sitcom.
Frasier Crane's first wife, Nanette (aka children's entertainer Nanny G) appeared in one episode of Cheers and two episodes of Frasier, and was played by a different actress each time.
The dog Eddie was originally played by Moose; over the course of the later seasons, Moose was replaced by his son Enzo.
Passions parodied the use of voice-over to announce a casting change when Mark Cameron Wystrach took over the role of Fox Crane in February 2006. The voice-over played out, and Tabitha, who was in the scene looked for the source of the voice-over, before it scolded her to open the door and meet the new Fox.
In The Fresh Prince of Bel-Air, Aunt Vivian's actress Janet Hubert-Whitten was replaced in the third season, due to an inability to come to a contract agreement and ongoing tension between her and Will Smith. She was replaced with Daphne Maxwell Reid who remained for the rest of the series. This was lampshaded at the beginning of the 5th season, when Jazz asked Will Smith who they got to replace Vivian this time and a Soap Opera Rapid Aging Syndrome-addled Nicky Banks answered "It's the same mom!" In fact it was lampshaded quite openly numerous times throughout the show. Will Smith often mugged for the camera after making these comments, which were generally ad-libbed.
Lampshaded in The Fast Show's Live Episode a recurring character was played some another actor and aged to 18 (presumably so they didn't have to deal with children in a live performance), and is greeted with "18, eh? You look so different, I hardly recognize you. Almost like a different actor!"
Blake's 7 did this with two major characters and one minor one.
Travis, The Dragon, is played by Stephen Greif in Season 1 and Brian Croucher in Season 2.
The very minor Federation bureaucrat Ven Glynd has two appearances in different seasons and is played by a different actor each time.
The voice of Orac was provided by Peter Tuddenham, who also voiced the Liberator computer Zen, after original Orac voice artist Derek Farr was unwilling to sign up as a regular cast member.
In The Munsters, Marilyn Munster was played by two different actresses: Beverley Owen (in the first 13 episodes) and Pat Priest (in the rest of the series). Marilyn was recast yet again for the follow-up theatrical film, Munsters Go Home with Debbie Watson. Nobody seemed to notice or care. Owen only worked on the series at all because of a contract obligation and quit at the first opportunity. Priest however, was greatly upset at being replaced for the film, especially since Watson was only cast because Universal was trying to push her as the next big teen idol.
In the 1981 telefilm, both Eddie and Marilyn were replaced (with K.C. Martel and Jo McDonnell respectively) because their original actors were too old.
Beginning with the 1988 reboot/sequel, all incarnations of the series have had different actors for all characters.
Also, Nate "Happy" Derman played Eddie in the original pilot instead of Butch Patrick (though this incarnation of the character acted more like a pet than a child), and the mother of the family was "Phoebe" played by Joan Marshall (basically a Mortica Addams knockoff) instead of Yvonne DeCarlo as Lily.
For the three Gilligan's Island telefilms, the entire TV series cast returned to reprise their roles... except for Tina Louise as Ginger Grant, since she blamed the role on destroying her acting career. In the first two telefilms, Judith Baldwin took over the role, while in the third, Constance Forslund played the character. Also, in the original test pilot, Kit Smythe was the original choice for Ginger before Louise was cast.
Somewhat odd example in Monk: Dale "the Whale" is played by three different actors in his three appearances: Adam Arkin in "Mr. Monk Meets Dale the Whale," Tim Curry in "Mr. Monk Goes to Jail," and Ray Porter in "Mr. Monk Is On The Run, Part 2". All three did the role in fatsuits and, under their makeup and prosthetic fat, looked quite similar and could have probably been passed off without many people noticing except that the second actor was Tim Curry, who made no attempt to disguise his trademark accent.
Porter seems to have done away with the accent.
Four different actresses played Trudy Monk. Stella Rusich played Trudy in the character's first four appearances, Melora Hardin then played Trudy for an additional ten appearances, Rose Abdoo was Trudy for one episode between Hardin's fourth and fifth appearances ("Mr. Monk and Little Monk"), and Lindy Newton played Trudy in the college flashback episode "Mr. Monk and the Class Reunion".
Benjy, Sharona's son, was played by Kane Ritchotte in the pilot, season 2 and the first half of season 3, and by Max Morrow in season 1 (except for the pilot). This was because the pilot was produced in Vancouver, on the West Coast (where Ritchote lived), and the regular season 1 episodes were filmed in Toronto, Ontario (where Morrow lived).
When Mystery Science Theater 3000 moved from local Minneapolis station KTMA to Comedy Central (then-called The Comedy Channel), Jim Mallon took over from Josh Weinstein as the voice of Gypsy. It's possible that most people never noticed since, at the time, Gypsy had very few lines, and was close to being The Unintelligible when she did speak. Years later, when Mallon stopped appearing regularly in front of the camera, Patrick Brantseg stepped in as Gypsy, with few differences in voice.
Later, when Weinstein left the show after the first season, Kevin Murphy stepped in for Weinstein as the voice of Tom Servo; but this was subverted since the difference was explained in-series as Joel tinkering around with things.
The departure of Trace Beaulieu, who played Crow T. Robot, when the series moved from Comedy Central to Sci-Fi Channel resulted in a change to Crow's voice when Bill Corbett took over the role. Crow's voice change was alluded to in the Sci-Fi opening credits, during which Crow proclaims, "I'm different!"
In a later episode, Crow is telling Mike (who's turning into a Were-Crow) what to expect from his transformation, and mentions that "Your voice is gonna change inexplicably every seven years or so."
In season premiere of season ten, Joel takes notice of Crow's different voice and says that Crow "changed his beak" (admitting that it was in fact a bowling pin).
Two of Jeeves and Wooster's characters are played by three different actors each (Madeline Bassett and Constable Oates) and Aunt Dahlia is played by a different actress every series. The total number of characters (some fairly major) who change actors at some point runs into double figures. This can result in a fair amount of confusion and arguments when watching the entire run, due to the show making no real effort to ease the transitions for the viewer. Not to mention having an established character suddenly become Martin Clunes is a little jarring...
This is made much worse by the fact that some of these actors later appear as different characters for example, one actress who started out as Madeline Bassett plays Florence Craye in later episodes.
In My Wife and Kids Claire was played by Jazz Raycole in the first season. Jennifer Freeman (who looks nothing like Jazz Raycole) plays her in the second onwards, when Freeman debuted as Claire her father Michael (Damon Wayans) even commented saying "I don't know what it is, but you look like a whole new person!". The reason was because Raycole's mother objected to the then upcoming "Claire's friend is pregnant" plot and pulled her daughter out of the show. Junior's girlfriend Vanessa was also played by two actresses (Meagan Good then Brooklyn Sudano).
YATR is not unique in this respect. Since American daytime soap operas have a tendency to feature the same characters for decades, it's not uncommon for roles to be recast on a temporary or permanent basis when an actor decides to go on to do something else, but the writers have more stories to tell using the character.
William Shatner's predecessor in Star Trek: The Original Series, Jeffery Hunter, played Captain Pike in "The Cage". This footage was later re-used in "The Menagerie", with Pike himself appearing a motionless deformity in an iron lung-type device. This was primarily to disguise the fact that Hunter was now a film star and thus unavailable; this new Pike was played by a lookalike (such as he is) named Sean Kenney. What's interesting is that Captain Pike was retconned into Kirk's predecessor, as well; he was the original Captain of the Enterprise, with Mr. Spock as his first officer. This is still canon in the Abrams film, in which Bruce Greenwood plays Pike.
Tora Ziyal was portrayed by three different actresses as the show went on: Cyia Batten in her first two appearances, Tracy Middendorf for one episode, and Melanie Smith for the rest of the series. The character was 19 years old when first introduced, but the producers decided to age up the actress (despite the original actress already being older than her character) to emphasise the character's maturity in preparation for developing a relationship plotline with an older male character to avoid any perception of cradle-robbing occuring (by the time the relationship was established, Ziyal was at least 21 years old and being played by a 34-year old actress).
Quark's mother was played by two different actresses (SCTV's Andrea Martin in her first appearance, and Cecily Adams, daughter of Don Adams, in all subsequent appearances), due to the original actress not being able to bear the prosthetics, but due to the heavy makeup and low frequency of her appearances, it's less noticeable.
Neral, the Romulan leader, was played by Norman Large in an episode of Star Trek: The Next Generation, then by the noticeably older and thinner Hal Landon Jr. in an episode of Deep Space Nine. Lampshaded somewhat by the official card game, where Neral's card states he "has not aged well under the burden of leadership."
In a Season 2 episode of Voyager, Tom Paris, under the influence of a telepathic alien, has a vision of his father, played by Warren Munson. When we meet the elder Paris in Season 6 (on Earth, working on a way to bring the titular ship home), he is played by Richard Herd, who continues to portray the character through the series finale.
Similarly the character of warp drive inventor Dr. Zefram Cochrane, who was played by Glenn Corbett in the Star Trek: The Original Series episode "Metamophosis" is played here by James Cromwell. (Corbett had already passed away by the time the movie was shot). Cromwell would later reprise the role (through an in-universe video, as the scene he appears took place 90 years after the events of First Contact) in the premiere episode of Star Trek: Enterprise
The UK sitcom All About Me replaced its star Meera Syal with Nina Wadia after one series, as Syal became more famous and moved on to bigger and better things.
Winning quite possibly the award for the strangest example of all time: Christina Crawford, appearing in The Secret Storm from 1968-1969, got an ovarian tumour. While she was off the show, they got a stand-in: Joan Crawford—her adoptive mother, and more than thirty years older than her.
Iconic Australian SitcomHey Dad..! did it with not one, but two characters. Simon Kelly was played by Paul Smith in 1987, then by Christopher Mayer from 1988-91. Simon's little sister Jenny was played by Sarah Monahan from 1987-93 and by Angela Keep from 1993-94. Jenny's change was lampshaded with a line like "You've really changed at that boarding school", but Simon's change was completely unacknowledged.
The Worst Witch featured three such changes. The first one saw Felicity Jones replaced as Ethel Hallow by Katy Allen for Seasons 2 and 3, which was explained away as a "makeover". Jones later returned for the role in the fourth season (Weirdsister College). Fenella Feverfew was played by Julia Malewski for the first season and Emily Stride for the third. The character of Miss Hardbroom was also played by two different actresses: Kate Duchene in the first three seasons, and Caroline O'Neill in The New Worst Witch. In fact, only Georgina Sherrington (Mildred) has appeared in all three incarnations of the show.
The child swap on Psych; Josh Hayden, the child actor playing Young Shawn, appeared only in the pilot. In other appearances, the part is played by Liam James and Skyler Gisondo.
The changeover from James to Gisondo is lampshaded when a character remarks that Young Shawn Version 2 doesn't look anything like Adult Shawn. Shawn replies, "We changed. Sometimes from week to week."
They did it with Young Gus, too. Carlos McCullers II replaced Isaah Brown after 5 episodes.
And Gus' father, who has been played by Ernie Hudson and Keith David.
In the second episode of Quantum Leap, it shows Sam's father as a separate actor. In a later episode when Sam leaps into a younger version of himself, his father is also played by Scott Bakula, just in make up to look older.
Boy Meets World combined Chuck Cunningham Syndrome with Suspiciously Similar Substitute; Cory's younger sister Morgan was played by two child actresses, in non-consecutive seasons. When the new Morgan appeared, she said she had been sent to her room, and was only now coming back down. Lampshaded when she mentioned in a dazed tone that she had been up there "a long time."
Also occurs to Topanga's parents, where they are almost completely different characters whenever they appear. Topanga's father is played by Peter Tork of The Monkees during the second/third season guest appearances, by Michael McKean in Season 6 and then by dark-haired Mark Harelik in the last season. While Peter Tork accentuated the character's hippie tendencies, the replacement actors made him more "normal". Her mother also changes actresses despite only appearing towards the end of the show, played by Annette O'Toole in the Season 6 finale and by Marcia Cross in the Season 7 appearances.
Many people forget that Danny McNulty as Harley Keiner was briefly replaced by Kenny Johnston for "Wrong Side of the Tracks" before being written out until Harely returned with McNulty reprising his role for one episode. McNulty also is reprising the role on Girl Meets World.
Joshua "Josh" Matthews, who was played by a non-actor in Daniel Jacobs (creator Michael Jacobs' real life son) in the Boy Meets World finale, is portrayed by Uriah Shelton in Girl Meets World.
Laurie from That '70s Show was played by Lisa Robin Kelly in Seasons 1-5 and replaced by Christina Moore (who was one of many short-lived MADtv cast members in the same vein as Simon Helberg and Taran Killam) in the 6th season.
Also of note is Jackie Burkhart's mother Pam was originally portrayed by Eve Plumb but when she returned from an extended vacation Brooke Shields had replaced her.
On Everybody Loves Raymond, in the season 4 episode "Hackidu", Amy's brother Russel owned a comic store and was played by Paul Reubens. In the Season 7 episode "Just a Formality", we meet Amy's brother again; not only is he now played by Chris Elliott, but his name has been changed to Peter. However, he still remembers Raymond coming to his comic store. He becomes a recurring character for the rest of the series.
El Chavo del ocho, Chavo's Love Interest Paty was played by two actresses; Rosita Bouchot (in two episodes) and Ana Lilian de la Macorra for the rest of the show (nearly 25 episodes because she was a very recurring character), no one seems to notice the change in look and attire.
The sisters' father appears for one episode in the first season, played by Tony Denison. In all subsequent appearances of the character, he was played by James Read, who looks nothing like the original actor. The change was never noted by the characters or explained.
Piper's friends Becca and Wendy appear in a Season 4 episode and then later show up in a Season 5 episode played by two different actresses.
The actress playing Harriet was changed on the very last minute for Family Matters' final season. The original actor felt that the show was suffering Seasonal Rot and wanted no more part of it.
On The O.C., Ryan's brother Trey switched actors from the second season onward, with no fanfare.
Marissa's sister Kaitlin is played by two different actresses, with the switch coming after the character returns from boarding school. A few characters remark on how much she's changed. (Seth: "Mini-Coop ... not so mini.")
My Big Fat Greek Life, the TV sequel to the film My Big Fat Greek Wedding, managed to snare every major actor from the film except for John Corbett, who had played the groom in said wedding. The series begins with his wife's mother telling him "You look different", then quickly commenting that her daughter does too.
Chloe Annett replaced Clare Grogan as Kochanski in Red Dwarf when she became a main character. Might be justified by her being from a parallel universe, but Lister reacts as if she's just like "his" Kochanski.
After a single episode as Kryten in series 2, David Ross was replaced by Robert Llewellyn when Kryten permanently joined the crew in season 3.
The character Gary Ewing first appeared on a two-part episode of Dallas played by David Ackroyd, who was replaced by the completely different looking Ted Shackleford when the character spun off to Knots Landing the following year. His wife Val, who had appeared in a few more episodes and was therefore more recognizable, was not replaced.
Dallas also set up one of these for Pam Ewing, as after Victoria Principal left the show the character supposedly died in a car crash, but later appeared with her head covered in bandages after extensive reconstructive surgery. However, she never did appear again.
There's also Donna Reed taking over the role of Ellie for a year after Barbara Bel Geddes' heart attack. Bel Geddes returned in the next season.
Jenna Wade was played by three different actresses; Morgan Fairchild for her first appearance in a 1978 episode, Francine Tacker for two episodes in 1980 and finally Priscilla Presley from 1983 onwards a series regular.
Goodnight Sweetheart is a British sitcom about a man who practices bigamy by time-travelling back to the 1940s and marrying another woman there. Both wives' actresses were changed at the start of the fourth season.
Seven different actresses were cast in the roles of Kate's three daughters on Petticoat Junction, with the first cast change happening even before the series started filming (an early example of Sharon Tate's amazing bad luck).
Gary, owner of the rival bar on Cheers, was replaced by a different actor for his second appearance. The interesting twist is that for the rest of the series they kept switching the actors (Joel Polis and Robert Desiderio) back and forth. Since Gary was usually only in one episode a season and the 2 actors looked alike, it's doubtful many people noticed.
Terminator: The Sarah Connor Chronicles, which continued on from the first two Terminator films (but not the third and fourth films), recast every character from the films who appeared on the show. Lena Headey replaced Linda Hamilton as the title character; Thomas Dekker took over the role of John Connor. This also applied to guest characters: Jonathan Jackson replaced Michael Biehn as Kyle Reese (who appears in flashbacks and as a blood-loss-induced hallucination), Bruce Davison replaced Earl Boen (who is retired) as Dr. Silberman, Tony Amendola replaced Castulo Guerra as Enrique Salceda, and a photo of Miles Dyson showed actor Phil Morris rather than Joe Morton. In the pilot episode, Sarah has a nightmare involving a Terminator played by Aaron James Cash. Although it's not clear, given what Sarah is likely to have nightmares about it's possible this was meant to be the same Terminator model played in the films by Arnold Schwarzenegger.
In similar fashion, the TV series spinoff of the The Net starred Brooke Langton as Angela Bennett, replacing Sandra Bullock from the film.
Long running (more than 4000 20-minute episodes so far!) Hungarian soap Barátok közt (Amongst Friends) has pulled it off three times, mostly combined with a short bus trip. All of them were female characters, first a rape victim visited her relatives in the countryside to forget and another actress came back. Huge lampshade was also hung as a character noticed that she became more feminine. Second, a girl who survived the car crash in which her boyfriend died went crazy, so she took a trip to her relatives in Ireland. The third character wasn't put on the bus, since she was quite new in the show, and the new actress looked similar to the old one. This is also a case of Real Life Writes the Plot, since all of the replaced actresses were in their graduation year.
The actors for every character in Australian TV show Round the Twist was replaced at least once, for the most part because of Real Life Writes the Plot: there was a gap of three years between series 1 and 2 and seven years between series 2 and 3, so all the kid characters were recast due to the actors growing too old; also, the original actors for Tony Twist (Richard Moir) and for Nell (Bunney Brooke) weren't rehired for series 3 because of illness (Richard Moir's Parkinson's Disease and Bunney Brooke's terminal cancer).
Amusingly lampshaded in Dream On. The second season starts with Eddie's face wrapped up in gauze in a hospital room. When the gauze is taken off, he appears to have had some Magic Plastic Surgery. However, everybody says that he doesn't look any different. Martin quips "A little younger maybe."
Granada produced two seasons of The Adventures of Sherlock Holmes with David Burke in the role of Dr. Watson. "The Final Problem" was his last episode, as he wanted to tone down his acting career and spend more time with his family. Edward Hardwicke picked up the role almost seamlessly in the next series, The Return of Sherlock Holmes.
Brian in Seacht was replaced with a completely different-looking actor between the first and second series. His personality also changed.
For one Season 1 episode, Lestat the Pomeranian dog who portrayed Claire's dog Mr. Muggles was unavailable, so his brother Beowulf filled in. The two dogs look noticeably different so the new dog was put in a jacket to hide this.
The Burns and Allen Show: Apparently the earliest example of this trope. Four actors had played Harry Morton by the end of the first episode of the fourth season. When Fred Clark, the third Harry Morton, decided to leave the show, George Burns replaced him in the middle of the first episode of the fourth season. In a scene where Blanche Morton was ready to hit her husband in the head with a telephone directory as soon as he came in, George entered, yelled "Stop!" and everyone froze, with the phone book uplifted. George then brought out the new actor, Larry Keating. There was some chitchat, with Clark and Keating saying how much they'd admired each other's work. When George called for the scene to resume, Keating entered and promptly got smacked on the head with the phone book.
In the popular Australian soap Home and Away, the character of Pippa was originally played by curly-haired blonde Vanessa Downing. She was replaced by Debra Lawrence an actress with straight, brown hair.
In The Restless Years, another Aussie soap, one character was seen in a hairdresser's, commenting "I hope my hair turns out ok". She then whipped the towel off to show that she'd changed from brunette to blonde and changed actresses at the same time.
The most famous instance concerns Jan in The Brady Bunch Hour. When Eve Plumb was unavailable for the variety series that aired in 1977, actress Geri Reischl stepped into the role. Parodied in The Simpsons Season 8 episode "The Simpsons' Spin-Off Showcase", said segment being titled The Smile-Time Variety Hour (one of three fictional pilots seen in the episode). A blond-haired teenaged girl named "Lisa" replaces the real Lisa, with the explanation that she refused to participate, "But thanks to some creative casting, you won't even notice!"
The other two Brady girls, Cindy and Marcia, have had Other Darrins. In A Very Brady Christmas, Cindy was played by Jennifer Runyon (Susan Olsen had just gotten married in the summer of 1988, when the movie was being filmed, and thus unavailable); in 1990's The Bradys, Leah Ayres took over the role of Marcia (Maureen McCormick declined to reprise her role).
In ER, Dr. Greene's daughter Rachel was played by Yvonne Zima for the first six seasons, then by Hallee Hirsh for all the character's appearances until the show ended. Similarly, Roger, the husband of Dr. Benton's baby mama Carla was played by Victor Williams in a few episodes, before being replaced by Vondie-Curtis Hall. Both were lampshaded somewhat by the fact that recaps of scenes from past episodes were shown, but with any shots of the old actors replaced with the new ones.
In Season 2 of Mighty Morphin' Power Rangers, Ami Kawai (Scorpina) was replaced by Sabrina Lu. Also, when Austin St. John, Walter Jones and Thuy Trang were fired partway through Season 2, a lot of the lines for Red Ranger Jason were done by a decisively different actor mimicking his deep voice during Ranger fights.
In Turbo: A Power Rangers Movie, Divatox was played by Hilary Shepard Turner, who was replaced by Carol Hoyt in Power Rangers Turbo, though Shepard did take over for the second half of Turbo and for Power Rangers in Space.
Amy Miller, who played Trakeena in Power Rangers Lost Galaxy, did not return for the team-up in Power Rangers Lightspeed Rescue, where Trakeena was played by Jennifer Burns. Reportedly, Miller did show up for the episode, but walked off the set when she found out the Lost Galaxy cast would essentially be playing second fiddle to a child actor. Danny Slavin (who played Leo, the Red Galaxy Ranger) separately walked off in a pay dispute before ADR could be done, so morphed scenes and some other parts of the episode feature the voice actor Christopher Glenn doing his best Leo impression. He later buried the hatchet and appeared in Forever Red in 2002 and traveled to New Zealand in 2013 for a cameo in Power Rangers Super Megaforce.
In Power Rangers Mystic Force, Barbara Goodson was replaced as the longtime voice of Rita Repulsa by Susan Brady, a New Zealand voice actress. This was Rita's second actress swap, as Carla Perez (who was Rita's body in American footage from season 2 of MMPR to PRIS) took over from Japanese actress Machiko Soga (season 1 of MMPR, via footage from the Japanese series Kyoryu Sentai Zyuranger and some original footage later shot for MMPR). Soga played Rita again in Mystic Force, though, again via Japanese footage.
Decade had the plot conceit of the main characters traveling through Alternate Universes and meeting alternate versions of past Kamen Rider characters, even when the character has the exact same name and backstory (see: Amazon, Tackle in the second movie). It is in fact very unusual for a Decade "Alternate Rider World" character to have the same actor as the original. Exceptions include most the Den-O cast, the original Kiva, and Black/RX.
Over in Super Sentai land, Toei apparently tries not to Other Darrin them unless really needed. A good showing of this would be the Gokaiger Goseiger Super Sentai 199 Hero Great Battle, due to the fact that they were employing nearly 200 stunt actors for the Great Legend War scene, they had the Gokaiger and Goseiger actors cover the non-guest starring Sentai heroes.
Before actor Zachary Quinto was cast as Sylar, the role was being played by various stunt doubles (usually noticeably older than Quinto) being shot from behind, half-obscured, and with a baseball hat. A voice message left by Sylar before Quinto was cast was recorded by voice actor Maurice Lamarche.
Similarly, actor Erick Avari had not been cast as Chandra Suresh when the first few episodes were filmed. Whenever Chandra appears in photographs (with Mohinder or on the back cover of his book "Activating Evolution"), different actors are used; one bearded, one in a turban. Some of these were later replaced by photos of Erick Avari for the DVD releases, but some were missed.
Twitch City recast the role of Rex Reilly between Seasons 1 and 2, lampshading it when talk show host Rex mentions his "on-air cranium transplant." However, this explanation is undone by the season premiere, for which a flashback to Nathan's appearance on the talk show was reshot with the new Rex.
On The New Adventures of Robin Hood, Barbara Griffin replaced Anna Galvin as Marion in Season 2, and then John Bradley replaced Matthew Poretta as Robin in Season 3.
1990's soap Sunset Beach has a bunch of these. One of the main characters got switched twice.
Bones had this with just a bit part. Benito Martinez (Capt. Aceveda of The Shield) played a one-off chacter Vega, an author whose fame came from following, and making famous, a serial killer "The Gravedigger". This killer was never caught, and abandoned for a few seasons. Suddenly "The Gravedigger's" back, and all suspects are rounded up again. Included is Vega, now played by Marco Sanchez. He's there mainly to be killed off halfway through, but they hardly looked alike beyond being tall and Latino.
Michelle, Cam's adopted daughter, is portrayed by Dana Davis, who got a starring role on another show for the next season and was replaced with Tiffany Hines.
The sketch The Whipmaster (on the season 18 episode hosted by Bill Murray), while not a real example as there was only one Whipmaster sketch, is about how this trope can go horribly, horribly awry when you replace the original actor (who was experienced with working a whip) with one that isn't.
On the actual show, the fact that the show has been on for a long time and has amassed a lot of cast members (both long-running and short-lived) has led to a lot of celebrity impressions being done by different cast members. Notable examples include:
Bill Clinton (played by Dana Carveynote as the young, draft-dodging, pot-smoking hippie Clinton, Phil Hartman, Michael McKean [during the show's much-loathed 20th season], Darrell Hammond, and Beck Bennett)
Barack Obama (played by Fred Armisennote to the outrage of some who think Armisen was not the right race to play him and the fact that Lorne Michaels turned down Donald Glover and Jordan Peele, who are black, skinny men who have good to passable Obama impressions until 2012, when Jay Pharoah took over)
Because the show took awhile to find a permanent black female cast member, there was no one to play Michelle Obama...unless you counted the cameo appearances by Maya Rudolph and that one time Kerry Washington hosted SNL and SNL made fun of itself for using a black female host to play multiple roles to cover up the fact that they didn't hire a black comedienne in the early half of season 39. When SNL finally buckled down and hired a black female cast member, they chose Sasheer Zamata as Michelle (with writer/cast member Leslie Jones, as her She-Hulk-esque persona).
George W. Bush was first played by Will Ferrell. When he left in 2002, Chris Parnell (who was just rehired after being fired for budget cuts) played him, followed by Darrell Hammond. In the middle of the 2003-2004 season, Will Forte played George W. Bush and from 2006 to the end of Bush, Jr.'s administration, Jason Sudeikis played George W. Bush (though whenever Will Ferrell comes back to host or cameo, he reprises his role).
Donald Trump has been played by Phil Hartman, Darrell Hammond, Jason Sudeikis (in a one-off sketch), and Taran Killam. Most of the current political sketches in the 2015-2016 season have ping-ponged between having Taran Killam as Donald Trump and having Darrell Hammond (who is back on the show as the new announcer following Don Pardo's death) as Trump, with Hammond looking and sounding the most like him.
Hillary Clinton is currently played by Kate McKinnon, though when Amy Poehler came back to host a season 41 Christmas episode, Poehler was cast as her (in fairness, it was because the McKinnon Hillary Clinton was being visited from her past self).
The announcer of "What Up Wit' Dat?" (the overly-long musical talk show recurring sketch with Kenan Thompson as DeAndre Cole) was originally played by Will Forte. When Will Forte left in 2010, Taran Killam replaced him. The backup dancers also changed; in season 35, they were played by Nasim Pedrad and Jenny Slate. When Jenny Slate was fired after season 35, she was replaced with Abby Elliott.
The long-running Canadian sketch comedy series Royal Canadian Air Farce originally featured founding cast member Don Ferguson as then-Canadian Alliance Party leader Stephen Harper in the early 2000s. Not long after, then-new cast member Craig Lauzon took over the role, possibly to allow Harper to appear in political sketches where Ferguson was playing Liberal leader and then-Prime Minister Paul Martin. Lauzon's take on Stephen Harper became one of his most familiar on the program, especially after Harper defeated Martin in the 2006 federal election.
Invoked on The Famous Jett Jackson when Executive Meddling wants to bring more gun-based violence to the Show Within a Show "Silverstone", which the actor playing the villain of the specific episode debuting the gunplay disagrees with the change. He is obviously fired and a new actor is brought in, the new actor's debut scene includes Jett's character Silverstone commenting on the villain's plastic surgery. Of course, the episode has An Aesop of "guns are bad" (Jett's father, a sheriff, had to shoot a criminal on duty and is traumatized by the event), so in the end Jett and the entire remainder of the crew threaten to quit, so the producer has no choice but to scrap the episode and ditch the guns idea. The original actor returns to film the original script of the episode, thanking Jett for his support.
Lost may or may not have invoked this trope. When Ben and Locke visit Jacob's cabin in Season 3, Jacob, in his split-second appearance, is "played" by the show's prop master Rob Kyker, who has long hair, a beard, and appears to be in his 40s or 50s. He looks absolutely nothing like Mark Pellegrino, the actor who plays Jacob in his many appearances in the Season 5 finale. However, there is evidence to suggest the man in the cabin was not Jacob. Additionally, Titus Welliver, who plays Jacob's unnamed nemesis, does bear a resemblance to Kyker, and is possibly the individual who impersonated Jacob in the cabin. If that is true, this would still be a case of The Other Darrin.
Done with Charlie's dad: made acceptable because you don't see his face the first episode.
Same case with Claire's mother: she has no lines in her first appearance and is only visible under bandages.
Dr. Quinn, Medicine Woman had an incident midway through the show's run where Erika Flores, who played Colleen, was abruptly fired and replaced by Jessica Bowman. Needless to say, the fandom was furious.
Being Human has "The Other Darrins". Two of the main trio and one other important character were replaced between the pilot and the series. Aidan Turner replaced Guy Flanagan as Mitchell, Lenora Crichlow replaced Andrea Riseborough as Annie and Jason Watkins replaced Adrian Lester as Herrick. These last two are especially noticeable because Lenora has tan skin and dark hair, while Andrea is pale and blond, and Lester is black while Watkins is white. The curious thing is that the pilot is still part of the plot, but once the series proper started they didn't re-shoot the episode so much as make new scenes with the new characters to bridge the gap.
The Inspector Lynley Mysteries had Lesley Vickerage as Helen, up until she separated from Tommy. Then in the last season she comes back played by Catherine Russell. This wouldn't be so bad if the two actresses looked anything like each other one notable difference is that Lesley's hair is short and black while Catherine's is long and brown and if they hadn't called attention to Helen's appearance in an episode. When you make Havers get haircut to look like Helen as a cover, and you make a big deal about how they look the same from behind, chances are fans will notice. Better yet, Vickerage was actually the second actress to play Helen the character also appeared in the first story ever shot, the pilot episode "A Great Deliverance", played by Emma Fielding!
In the pilot for WKRP in Cincinnati, the mother of the station manager was played by Sylvia Sidney. She wasn't available for the series because of other acting commitments, so she was replaced by Carol Bruce, who was about a decade younger and much taller than Sidney. A subsequent Clip Show then had the scene from the original pilot re-shot with Bruce.
The roles of Quinn's parents on Sliders changed hands almost every season.
Brain-tissue-harvesting Evil Brit Col. Rickman was played by Roger Daltrey in his first appearance. Perhaps realising it might have been wiser to cast an actual actor, Neil Dickson replaced Daltrey as Rickman in all his subsequent episodes.
Brass's daughter Ellie in CSI was played by two very different-looking actresses Nicki Aycox◊ in her first appearance, Teal Redmann◊ in her subsequent ones. The fact that there was a multi-season gap between her appearances took the edge off of this somewhat.
CSI NY had a variation on this. The woman whose photo was used as that of Claire, shown to Reed by Mac in season 4, is not the actress who played Claire in the season 8 eps 'Indelible' with its flashbacks and 'Near Death' with Mac's Near-Death Experience encounter with her.
Lucy Messer borderlines; the need for a different actress as she grew older was natural, but even when there was only 6 months skip between s8 and s9, a new actress was still used.
In Dynasty, all four of Blake's children switch actors.
On the old Batman live-action TV series, the role of Catwoman went from Julie Newmar to Lee Meriwether for Batman: The Movie, and then in the final season it went to Eartha Kitt.
John Astin replaced Frank Gorshin as The Riddler in one story.
The Australian fake lifestyle show Life Support used this a lot.
Penne was played by Abbie Cornish during season one, but replaced by Alison Barnes for the second and third seasons. This was heavily lampshaded when Todd suspected that "something was wrong" with Penne, but Sigourney reassured him by showing flashbacks from the first season.
When the character of Trapper John McIntyre (played in the movie by Elliott Gould) left M*A*S*H, he reappeared in the stateside medical drama Trapper John MD. Wayne Rogers played him on M*A*S*H, Pernell Roberts on Trapper John. (Justified in that the latter series takes place some 25 years after the former and thus involved a much older character.)
Speaking of M*A*S*H: Father Mulcahy was played by George Morgan in the show's pilot before William Christopher took the role.
Only Radar and a few minor characters are played by the same actor in the film and the TV series. Every other major character is an example of the trope.
Margaret Houlihan's fiancé, Lt. Donald Penobscot, was played by a different actor in each of his two appearances on the show. Ditto visiting nurse Meg Craddy.
Three different actresses played Rosie (of Rosie's Bar) during the show's run.
There were lots of different actresses who played "Nurse Able" or "Nurse Baker" in various episodes.
Mildred Potter (Colonel Potter's wife) appeared in M*A*S*H only as a photograph (of Harry Morgan's real-life wife Eileen Detchon), but in the unsuccessful spinoff AfterMASH, she was played by Barbara Townsend in the first season and Anne Pitoniak in the second (the OTHER Other Darrin?).
In the Australian serial drama Ocean Girl the mother of two of the central characters is recast after Season 2 to be played by a different actress in Seasons 3-4 without explanation.
In FlashForward (2009), the actor playing Dylan Simcoe was recast in the middle of filming the pilot. So some scenes feature the first and some the other, and the credits credit "Dylan #1" and "Dylan #2". The second one has been consistent ever since.
In The Waltons, Robert Wightman took over for Richard Thomas as John-Boy in the last two seasons of the show. Thomas eventually returned for a series of early '90s reunion movies, however.
Deirdre Barlow's daughter Tracy was portrayed by child actresses Christabel Finch and Holly Chamarette before switching to Dawn Acton from her late teens onwards. All three portrayed the character in a broadly consistent way as moody, insecure and eventually evolving into something of a Goth. From 2002, she was played by Kate Ford. Funnily enough Tracy's own daughter Amy underwent this, being at first played by Amber Chadwick for four years and then recast with Elle Mulvaney. Two other actresses had played her when she was just a baby.
Tracy's stepsiblings Peter and Susan Barlow (originally played by actual twin babies) have been repeatedly Other Darrined since they were sent to live with their late mother's parents at the age of six in 1971. At one point, the original actress (apart from the baby) to play Susan returned to the role, at another, Peter was played by the real life son of Ken Barlow's actor, who has since taken the role of another of Ken's sons.
Nick Tilsley was played by Warren Jackson for fifteen years and then went to live in Canada. When he returned a year later, he was played by Adam Rickitt. Years later he moved to Nottingham and was played by Ben Price when he returned again.
Liam and Michelle's mother Helen was first played by Sorcha Cusack. After Liam's death, she visited again now played by Dearbhla Molloy.
Ned Banks on Ghost Whisperer. Introduced in Season 2 with actor Tyler Patrick Jones in the role, who was replaced by Cristoph Sanders in Season 3. Noteworthy because Sanders looks nothing like Jones, being taller, blond (Jones has dark hair), and noticeably older.
The pilot episode of A Nero Wolfe Mystery, "The Golden Spiders", has Saul Rubinek playing Wolfe's freelance associate Saul Panzer, and Gerry Quigley playing the reporter Lon Cohen. The first episode after it becomes a series, "The Doorbell Rang", has Rubinek playing Cohen, and Conrad Dunn plays Saul Panzer. This casting remains consistent for the rest of the series.
In May 2010, Erin Mullally replaced James Sorensen as Declan Napier.
In 2008, the actress playing Libby Kennedy (Kym Valentine) contracted severe pneumonia and was replaced for four weeks by Michala Banas, with no explanation given to the audience.
Additionally, for people who grew up watching Neighbours, the relationship between Scott and Charlene and the real-life romance between their actors, Jason Donovan and Kylie Minogue, was the main event of the late eighties ... but Jason Donovan wasn't the original Scott. That was Darius Perkins.
Todd Macdonald replacing Scott Major as Darren Stark.
Lucy Robinson has been played by three actresses: Kylie Flinker, Sasha Close and the longest, and most recent, Melissa Bell who returned to the role in 2013 after a number of years absent.
Wonderfalls does this with Eric's wife Heidi. In Eric's honeymoon flashbacks she's played by Corry Carpf. Later, when the character actually appears in the series, she's played by Jewel Staite.
The original version of Survivors had at least three characters replaced; two of the switches (Ruth and Lizzie) happened between seasons, while Vic had to be replaced when his first actor had a nervous breakdown.
The youngest daughter of Bill and Barb Henrickson in Big Love suddenly grew up and changed appeareance in the fourth season; Jolean Wejbe was replaced by Bella Thorne. No one mentioned anything.
Farscape spoofs this in "John Quixote" by having an overweight male actor playing the role of Zhaan (as a piece of misdirection for the original actress appearing later in the episode).
The Peacekeeper Wars miniseries introduces a different actor to play Jothee, who had last appeared two seasons previously. Slightly lampshaded by John Crichton remarking how much Jothee had grown.
Veronica Mars originally aired with Backup, the title character's dog, being portrayed as a bulldog (by a dog called Gordo). Subsequently it was a pit bull (played by a dog called 'Lefty') not only a different colouring entirely (changing from brown spots on white to tan all over) but a breed change. This was because, despite having one and a half months to prepare, the trainer had failed to teach the original dog-actor the required stunt and so the dog had to be replaced. However, no hint was given in the show that anything was amiss, despite the replacement dog also being much larger than the original.
The 1960s sitcom The Mothers In Law replaced without comment one of the principal actors, rotund, mustachioed Roger C. Carmel (Harry Mudd on Star Trek) with bald, bespectacled Richard Deacon (Mel Cooley on The Dick Van Dyke Show).
Rome started off with 16-year-old Max Pirkis playing 11-year-old Octavian. As the series covers over 20 years of history over only two seasons, they had to recast him about halfway through, as Pirkis didn't look old enough to play Octavian as an adult. Enter 27-year old Simon Woods.
Yet oddly subverted with Vorena the Elder, who is played by the same actress through the entire series, despite the fact that her character starts out younger than Octavian and should by rights be at least in her mid-thirties by the time the series ends. (They do play it somewhat straight with young Lucius and Vorena the Younger, casting older children, but neither is even close to the age they should be by the end of the series.)
All My Children, like all daytime soaps, has recast characters countless times. However, in 2007 they decided to have fun with it by transitioning actresses playing Babe in mid-hug with her mother Krystal. Alexa Havins went in for the hug and Amanda Baker pulled back from it. See it here.
On Back To You, Lily Jackson replaced Laura Marano as Gracie a little over halfway through the season.
Played straight and lampshaded with Allison Stark in Til Death, even going as far as (sort-of) namedropping the trope and occasions on other shows where this has happened. Allison's boyfriend has a minor case of Medium Awareness and is therefore the only character on the show to notice the change.
Somewhat lampshaded in Meet The Browns when Logan Browning replaced Brianne Gould as the character Brianna for the second season. Upon first seeing her, Brown asks, "Who are you?" Brianna replies, "I'm Brianna." To which Brown says, "You a lie!" He seemed to be the only one to realize that the actress for the character had been switched.
Spartacus: Blood and Sand is a strange example, in that the changeover was publicly announced by the actor and the showrunner well in advance of the new actor's appearance: Liam McIntyre is replacing Andy Whitfield in the titular role of Spartacus for Season 2 after the latter was diagnosed with non-Hodgkin lymphoma (which proved to be fatal in September 2011), and therefore couldn't return for the production of the show's second season. It's worth noting that when Whitfield was first diagnosed, they created a prequel series while he underwent treatment. When it became apparent he wouldn't recover, they recast the role.
Lesley-Ann Brandt, who played Naevia in Blood and Sand and Gods of the Arena, was replaced by Cynthia Addai-Robinson for Vengeance due to Brandt wanting more money.
Days of Our Lives did an unusual take on this. Philip Kiriakis was played by Jay Kenneth Johnson until 2003 when he was replaced by Kyle Brandt in the usual manner. In 2006, Phillip had been injured in the military and had to receive facial surgery that made Him look like a different person and was then played by... Jay Kenneth Johnson.
The character of Mike Horton is perhaps the ultimate example. He has been recast 13 times!
On the Emmy-winning public access sitcom Elvis And Slick Monty, the actor for Elvis changed after the pilot, then again after the first season concluded. This was lampshaded when the second season opened with the characters watching the 10th season premiere of Family Matters. Slick explained the reason for the new Harriet, but Elvis would have none of it.
In the pilot for Blossom the title character's dad is played by Richard Masur, who doesn't look much like Ted Wass (who played the dad in the series).
Network executives didn't like the idea of Dirk Benetton playing Faceman in The A-Team, which is why Tim Dunigan plays him in the pilot.
The governor of Hawaii in the pilot for the original Hawaii Five-O was played by Lew Ayres; for the series he turned into Richard Denning but oddly enough, Lew Ayres later appeared on the series in another role!
Staying with Five-O, Tim O'Kelly played Danny Williams in the pilot but was replaced with James MacArthur for the series; and the recurring character of State Department official Jonathan Kaye was played by six different actors (including the very-dissimilar types of James Gregory and Tim O'Connor).
In the gay vampire series The Lair the actor for the character Jonathan changed between Season 1 and Season 2 and the actors looked so unlike (they had the same hair colour) that it was impossible to tell they were even the same person until the second was called Jonathan. The second actor was only used for one episode due to the character being written out.
Mrs. Peacock, who makes appearances in a few Are You Being Served? episodes, was played by two actresses: Diana King in her first two appearances, and Diana Lambert in a third.
Diana Lambert is one of several actors who made multiple appearances in the series as different characters; in her first appearance, she played a customer credited as "the six-pound fox" (so named because her character bought a fox fur wrap deeply discounted to six pounds by Mrs. Slocombe, who had hoped to purchase the wrap herself).
The Adventures of Robin Hood had two different actresses play the role of Maid Marian: Bernadette O'Farrell in series 1-2, and Patricia Driscoll in series 3-4.
In the soap Another World, the role of Rachel Davis Matthews Cory was originally played from 1967 to 1972 by Robin Strasser (who later played Dorian Cramer Lord on One Lifeto Live). Victoria Wyndham took over the role in 1972, and she became the best-known Rachel Cory.
On Home Improvement, Jill's sister Robin appeared in two episodes and was played by a different actress each time.
In Carrusel, when Fermin's first actor (Augusto Benedico) was no longer available, he was replaced by Armando Calvo who was and looked 10 years younger than the first actor. Also, the actress who played Maria Joaquina's mother Clara was replaced.
On Grace Under Fire, the title character's son Quentin was played by three different actors Noah Segan in the pilot, then Jon Paul Steuer, and Sam Horrigan in the final two seasons. The second switch is notable for also being a case of Soap Opera Rapid Aging Syndrome, as Quentin went from a pre-teen to a fifteen year old.
When Gleason was on the Du Mont network's Cavalcade of Stars, Pert Kelton played Alice. Kelton's husband had been blacklisted when Gleason moved to CBS, and her career suffered due to guilt by association.
Audrey Meadows, who is most identified with the role, took over when the show debuted on CBS.
Sheila MacRae assumed the role in a couple of TV specials between 1966 and 1973.
Elaine Stritch played the role in the first outing on the DuMont show.
Stritch was replaced by Joyce Randolph, who is most identified with the role.
In the 1966-73 specials, Jane Kean assumed the role.
In the first season of the original series, Jeannie's mother was played by, in "My Hero", Florence Sundstrom; in "What House Across the Street?", Lurene Tuttle. In the fourth season, expanding on the trope of Barbara Eden herself playing Jeannie's sister, she twice played her mother.
Gilmore Girls was pretty good about keeping actors that played recurring characters (and even recycled actors when the character would leave the show) except in two cases, one notable and one you could be forgiven for not noticing.
Mia, an important background character, who was the owner of the Independence Inn and a surrogate mother for Lorelai and Rory appeared in Season 2 for a single episode by Elizabeth Franz. When Mia appeared in the final season, she was suddenly played by Kathy Baker with no explanation.
Cesar, one of the servers at Luke's Diner, would occasionally appear in the background for the first two seasons played by a tall, thin actor, but had no scenes or lines. In the later seasons, he was played by Aris Alvarado, who was chubby and looked nothing like the first actor.
Disney's The Swamp Fox series replaced the actress who played Marion's fiance, Mary Videaux, after two episodes. The first was a light blonde, and the second had auburn hair.
While many members of the cast of Clueless appeared on the series either in their film roles (Elisa Donovan, Stacey Dash, Wallace Shawn) or guesting as other characters (Paul Rudd, Breckin Meyer, Brittany Murphy), for the ABC episodes Dan Hedaya (Cher's father) was replaced by Michael Lerner; when the series moved to UPN he in turn was replaced by the more handsome and much slimmer Doug Sheehan (his character was said to have gone through detox!). Alicia Silverstone, on the other hand, was replaced with Rachel Blanchard from the word go.
Happened with the voice over included in One Life to Live, when the original Todd Manning was replaced by another actor.
The trope was turned on its head when James De Paiva, the original Max Holden, was replaced by Nicholas Walker. The show explained that he looked different because of an accident which had required plastic surgery to replace Max's face. But then De Paiva came back to the show, and there was no explanation as to why he looked like his old self.
Bob West, the familiar original voice of Barney, retired from the role in 1999, then Duncan Brannan took over for three years, then he was replaced by Dean Wendt.
The One, the Big Bad in the second season of Martial Law, was initially never seen and only heard speaking with the voice of Tim Curry. When he eventually showed up to take care of business personally not only did he look like fellow British actor Christopher Neame (because a climactic fight between Sammo Law and Tim Curry would have too ridiculous for words, thanks to Curry not exactly being the physical type), but the "Previously on Martial Law" bits featuring Curry's voice were redubbed by Neame (and it's very noticeable).
Midway through Tinsel Season 2, Uzo Egereonu left the show and Funmi Holder took over the role of Amaka Okoh.
Funlola Aofiyebi-Raimi replaced Juliet Asante as Brenda Mensah.
In Season 5, Leonora Okine replaced Mathilda Obaseki in Season 5 as Angela. Also an example of Replacement Scrappy.
During a dispute with the producers, Clayton Moore was replaced with John Hart as The Lone Ranger for one year. Moore eventually returned to star for the rest of the series' run.
The show replaced the actress/stuntwoman April Weeden-Washington who played Nikki Wood in season 5's "Fool for Love" with another actress K.D. Aubert for her several appearances in season 7.
There's also the unaired pilot used to pitch the show where Willow was played by Riff Regan. Alyson Hannigan took over in the main series.
And Buffy's first watcher, Merrick. The actor playing him in Buffy and Angel's flashbacks was very different from the movie's Donald Sutherland. Probably because Whedon imagined him like the series version and the filmmakers changed it.
In the Buffy movie on which the show is based, Buffy is played by Kristy Swanson. In the show, she is played by Sarah Michelle Gellar. Therefore, Buffy is this to anyone who has seen the movie.
In the non-flashback footage of "When She Was Bad", the person under all that makeup playing The Master is David Boreanaz instead of Mark Metcalf. Furthermore, in the first Buffy game for Xbox, he's voiced by D.C. Douglas.
The enormous brute Gregor Clegane is played in the first season by 7' tall Conan Stevens, but he left the show to be in The Hobbit. In his place, the showrunners tapped Ian Whyte, who already had experience on the show as a White Walker. While one inch taller than Stevens, Whyte was very gaunt and skinny, and did not suit the character well. Possibly for this reason, the part was recast again, this time with Iceland's Strongest Man Hafþór Júlíus Björnsson (6'9" for those keeping score at home).
Also in season four, Michiel Huisman took over the role of Daario Naharis from Ed Skrein, who left to star in The Transporter Refueled.
Dean-Charles Chapman takes over the role of Tommen Baratheon from Callum Wharry, making for a rare case of an actor being both The Other Darrin and You Look Familiar (as Chapman previously portrayed Martyn Lannister, a character with a comparatively small part).
Rorge, Biter, Beric Dondarrion and Selyse Baratheon appear briefly as extras long before their characters are fully integrated to the series's cast. In both cases, their actors were re-cast. Also, Steve Blount portrayed a one-line-wonder character who was never addressed on screen but credited by HBO as "Rickard Karstark". John Stahl, who looks nothing like Blount and was given different make-up, took over the character in the second season.
In what has to be the strangest case of this ever on the show, for the first two seasons a "featured extra" with long white hair and a grey beard named Dennis McKeever portrayed the First Builder of the Night's Watch, Othell Yarwick. His character is featured in scenes with an unnamed Night's Watch senior officer portrayed by Brian Fortune. Fortune's character, who has darker hair and no beard, is the one to take newly-minted Stewards Jon Snow and Samwell Tarly to a Weirwood tree to speak their vows, which would seem to make him First Steward Bowen Marsh (who did so in the novel). McKeever is seen in a few scenes during the second and third seasons, but Fortune doesn't appear again until Season Four, whereupon his character is addressed as "First Builder Yarwick"!
Cadfael had a different actor play Hugh Beringar in each of its three seasons: Sean Pertwee, Eoin McCarthy, and Anthony Green. Derek Jacobi says he naturally has a favorite of the three but won't say who.
Spy features Phillip Quill, Judith's boyfriend, being played by Mark Heap in season two instead of season one's Tom Goodman-Hill. This is, hilariously lampshaded in Heap's first episode as Philip:
Philip: I know, I look different, don't I? It's the hair...
The television adaptation of The Aldrich Family, which ran from 1949 to 1953, had so many cast changes that each season featured an almost entirely new central cast. In all, fourteen different actors and actresses were rotated in and out of four of the five major roles:
Protagonist Henry Aldrich was played by Robert Casey, Richard Tyler, Henry Girard, Kenneth Nelson, and finally Bobby Ellis.
Henry's sister Mary was played by Charita Bauer, Mary Malone, and June Dayton.
Henry's mother Alice was played by Lois Wilson, Nancy Carroll, and Barbara Robbins.
Henry's best friend, Homer Brown, was played by Jackie Kelk, Robert Barry, and Jackie Grimes.
The lone aversion was Henry's father Sam, who was played throughout the series by House Jameson (who also played the role on radio).
Andre The Giant played the first Sasquatch. Beginning with "The Return of Bigfoot" and thereafter, Ted Cassidy replaced him.
Glee's Season 3 launch released a slew of fandom-bending changes, none explained with so much as a hand wave, and the more jarring of which was Rachel Berry's dads featured in a series of photobooth pictures in the series pilot would be played mid-season by Jeff Goldblum (whose pilot doppelganger was bald) and Brian Stokes Mitchell (whose pilot doppelganger was of a significantly darker complexion).
The TV series Assignment: Vienna had its entire regular cast made up of Other Darrins the pilot film, Assignment: Munich (even the location was a case of The Other Darrin) starred Roy Scheider, Richard Basehart and Werner Klemperer, but Scheider elected not to do the series because he thought films were his future (seaQuest DSV notwithstanding, he was right); hence all three leads were replaced by Robert Conrad, Charles Cioffi and Anton Diffring respectively, with filming changed to Vienna so the 1972 Olympics wouldn't disrupt production.
Phyliis (one of three spinoffs of The Mary Tyler Moore Show) had one of the most tragic examples of this trope: Barbara Colby (who played Phyllis Lindstrom's boss) was replaced by Liz Torres when she was killed in a drive-by shooting after four episodes had been produced.
Season 2 of Last Man Standing saw some of this, the most notable example being the older daughter Kristin, who's actress changed from Alexandra Krosney to Amanda Fuller for "creative reasons". In addition, her boyfriend Ryan was played by Nick Jonas as a guest star in Season 1, but has since been played by Jordan Masterson after the character became a regular. In addition, their son Boyd was originally played by the twins Evan and Luke Kruntchev for his Season 1 appearances, and by Flynn Morrison after the character was slightly aged up in Season 2.
Ed McMahon was the original host of NBC's Missing Links in 1963. He was replaced by Dick Clark when the show moved to ABC six months later due to his comittments with NBC.
On Concentration, Hugh Downs turned the reins of hosting over to long time announcer Bob Clayton at the start of 1969, but NBC wanted to go with McMahon. When ratings started to tumble, NBC switched to Clayton.
From, strangely enough, The Price Is Right. For the first three seasons, there were two models; Janice Pennington (a blonde) and Anitra Ford (a brunette). Around late July 1975, Anitra took a leave of absence and another model filled in: specifically, a blonde named Dian Parkinson, who had previously filled in for Anitra in mid-April (and hence, a natural choice). Not-so-naturally, beginning on August 19 she started to wear a dark wig and be addressed as "Anitra". Even with a wig there wasn't really much resemblance, so why Price felt they needed to do this is a mystery. When Anitra came back between early September and late October, Dian became the show's third model and was allowed to be herself again.
And also, Drew Carey taking over from Bob Barker as host in 2007. There was also Dennis James and Doug Davidson, both of whom hosted syndicated nighttime editions, and all four could be Other Darrins to original host Bill Cullen.
Original Wheel of Fortune host Chuck Woolery left in 1981 after his request for a raise was turned down. Pat Sajak, then meteorologist for Nashville's NBC affiliate WSMV, has been the host of the nighttime show since. He hosted the daytime show up until 1989 when he departed for his ill-fated CBS late night show. San Diego Charger placekicker Rolf Benirschke filled the host spot until July 1989 when the show switched to CBS and Bob Goen took over. Goen remained with the daytime show through its return to NBC and its course run to September 1991. On the same show, original hostess Susan Stafford quit in 1982, and Vanna White (who still holds the role to this day) took over.
Garry Moore pulled this twice. In 1966, he left I've Got A Secret and turned the moderator seat over to Steve Allen. In 1977, he retired from TV and after hosting the syndicated To Tell the Truth since 1969 was replaced with Joe Garagiola.
The NBC 1990 reboot of To Tell the Truth saw the host chair filled thrice, first with Gordon Elliot, then Lynn Swann, then for the balance of the show with Alex Trebek. On top of that, the pilot (hosted by Richard Kline) accidentally aired on the East Coast, and Mark Goodson had to fill in for Trebek on two episodes because Trebek's wife had gone into labor.
Wally Bruner left as host of What's My Line? in 1974 and was replaced with Larry Blyden for the show's final season. Speaking of Blyden, he was to host ABC's Showoffs that summer of 1975 but was killed in an auto accident. The clips used in ABC's promos for the show had Blyden hosting but was he was never shown in those clips. The host job went to Bobby Van.
The Name's The Same (ABC, 1951-55) went through Robert Q. Lewis, Clifton Fadiman, Dennis James and radio comedians Bob Elliot and Ray Goulding as moderators.
Tom Kennedy filled in for Allen Ludden on Password Plus in 1981 after Ludden fell ill. He died soon after and Kennedy became the show's permanent host.
Family Feud has had a total of six hosts since it premiered in 1976 (eight including Ricki Lakenote who hosted an edition of the game as part of Game$how Marathon in 2006 and Al Rokernote who hosted the Spin-OffCelebrity Family Feud on NBC in 2008), with four of those host changes occurring on the current version alone: Louie Anderson (1999-2002), Richard Karn (2002-2006), John O'Hurley (2006-2010), and Steve Harvey (2010-present).
Ray Combs replaced Richard Dawson as host when the show Channel Hopped to CBS in 1988; when Combs was fired from the syndicated version six years later, Dawson was brought back to replace him for one season, effectively Darrining the Darrin.
The Spin-OffCelebrity Family Feud was hosted by Al Roker for its unspectacular summer 2008 showing on NBC. When the show returned in summer 2015, this time on ABC, current Feud host Steve Harvey served as emcee instead.
The Timmy era of Lassie started with Cloris Leachman (of The Mary Tyler Moore Show fame) and John Shepodd as Timmy's parents and later replaced them with the more familiar June Lockhart and Hugh Reilly about a season in.
On The King of Queens, Deacon and Kelly's sons were played by several different actors over the course of the series. Then again, they were extremely young, so most casual viewers probably didn't notice.
Also happened with Spence's mom Veronica. In her first appearance, she's played by actress Grace Zabriskie, but in all her subsequent appearances she's played by Anne Meara (meant to be an in-joke, since Meara is Jerry Stiller's Real Life wife, and Veronica was depicted as being in love with Stiller's character Arthur). What makes it really Hilarious in Hindsight is that in that first episode where Zabriskie had played Veronica, Meara had appeared as a completely different character who had also harbored a crush on Arthur!
How I Met Your Mother: Robin's father was portrayed by Eric Braeden in season 4, but is currently played by Ray Wise. Tom, Barney's brother-in-law, was played by an unnamed actor for a picture◊ and can also be seen to be Caucasian in the later wedding scene (although only the top of his head can be glimpsed). Later on season 7, he was portrayed by Jai Rodriguez, creating a weird ethnicity◊ switch.
Drake & Josh: Helen Dubois is usually played by Yvette Nicole Brown, but once was played by Frances Callier in the episode Little Diva, from the second season.
Nineties British sitcom Birds of a Feather, about two sisters coping together while their husbands were in prison, had two cast changes, in that both actors who played the husbands were replaced. Chris was recast for Series Two up until the final series, at which point, Daryl was replaced as well while Chris was re-Darrined back into his Series One actor.
The pilot for the original Law & Order, shot in 1988, cast Roy Thinnes as Manhattan DA Alfred Wentworth. When the show made it to series two years later, Thinnes was unavailable, so Steven Hill was cast instead as DA Adam Schiff. While technically, the two are different characters and the trope wouldn't normally apply, NBC rather inexplicably aired the pilot in the middle of the show's first season. Thus, when viewing the episodes in their original broadcast order, the DA suddenly changes to a completely different person and back again with zero explanation.
In one episode of Law & Order, ADA Claire Kincaid was portrayed by Jacqueline Hennessy, the identical twin of Jill Hennessy, who usually played the character. Somewhat unusual for this trope in that it's not noticeable unless one is actively looking for it.
The pilot episode of Walker, Texas Ranger cast Gailard Sartain as C.D. Parker. In episode 4, Noble Willingham replaces him and continues the role until he would pursue politics, leading to the Put on a Bus / Bus Crash of his character.
This trope is so rare in Latin American television, it was somewhat of a minor scandal when the Mexican Soap OperaNada Personal changed the actress of the main heroine, from Ana Colchero to Christianne Gout, with only a small explanation at the beginning of a chapter that bordered on a Lampshade Hanging.
In Season 4 of the Singaporean television series Point of Entry, Jack Yang replaced Carl Ng as Glenn Chua.
The talent show Spanish Archer, broadcast on the very cheap UK cable network Live TV, played this for laughs. The host character "El Bow" changed actor part-way through the run from a man to a woman.
The actor playing the electrician in the pilot for NewsRadio was replaced in the second episode with Joe Rogan, who made the character his own and made him an Ascended Extra.
On The Millers, Eve Moon was replaced by Lulu Wilson as Mikayla halfway through the first season. Aside from the obvious physical differences, Lulu is more expressive and plays the character a bit goofier than Eve.
In the 2010s BBC adaptation of P.G. Wodehouse's Blandings, Beach the butler was recast from Mark Williams in series 1 to Tim Vine in series 2.
Happened on Hope And Faith when Nicole Paggi was replaced with Megan Fox as the teenage daughter Sydney after the first season. The show is credited as a big stepping stone in Megan Fox's career, but she looked nothing like Nicole (who was a blonde. Megan was a brunette), and even though she was technically 9 years younger, she looked much older, old enough to be her aunt Faith (played by Kelly Ripa)'s sister. Jansen Panettiere, meanwhile, was replaced with Paulie Litt as son Justin after the pilot.
For the TV series of Down and Out in Beverly Hills, Evan Richards (as Max) and Mike the Dog were the only ones to repeat their roles from the movie.
In the TV series of The Saint, the only character from the Leslie Charteris works other than Simon Templar to appear on anything like a regular basis was Chief Inspector Teal in his first appearance ("The Man Who Was Lucky") he was played by Campbell Singer, then he turned into Wensley Pithey in "Starring The Saint," then Norman Pitt took the role in "The Elusive Ellshaw" before Ivor Dean (who'd previously appeared on the series in "Starring The Saint") was cast in "Iris" and played the inspector for the rest of the run. But when Return Of The Saint came along, Roger Moore was unavailable (which was due to his commitment to the James Bond film franchise), so Ian Ogilvy took over the role, despite that the series was originally conceived as Son of the Saint, with Ogilvy's character identified as the offspring of Simon Templar. As production neared, it was decided to drop the relative angle and make the series about the original character, albeit updated to the late 1970s.
A weird in-universe example in The Heart She Holler; each season takes place in an alternate universe, where the most prevalent difference is that one character looks entirely different. In season 2, Hurshe Heartshe looks like Amy Sedaris instead of Kristen Schaal, and in season 3, the sheriff looks like Scott Adsit instead of Joseph Sikora.
In Arrow, Linda Park made a brief appearance in one episode, portrayed by Olivia Cheng. When the character became an Ascended Extra in the Spinoff, The Flash, she was recast with Malese Jow taking the role.
King Koopa's Kool Kartoons was a local show that aired on KTTV channel 11 in Los Angeles, California (which at that time was also airing The Super Mario Bros. Super Show). In this show, "King Koopa" (a costume worn by a live actor) was originally voiced by Christopher Collins (AKA: ChrisLatta), but was later replaced by Pat Pinneynote Whom some viewers may know as the voice of the Mighty Mouse in "The New Adventures" series from 1987..
In the Twin Peaks prequel/concluding movie Twin Peaks: Fire Walk with Me, most original cast members were either brought back for at least a few scenes, or had their characters simply alluded to rather than present on screen. However, Donna Hayward who, as Laura's best friend, was too important to the plot to simply write around was re-cast with Moira Kelly, since Lara Flynn Boyle declined to return (reportedly due to her unpopularity with the fandom after she was blamed for a particularly disliked piece of Executive Meddling towards the end of the show's run).
When Modern Family's Cam and Mitchell first adopted their daughter Lily, twins Ella and Jaden Hiller played her on-screen. After two seasons, Aubrey Anderson-Emmons took over and has played her ever since.
In the first episode of Die Kuhflüsterin, Thommy Mommsen is played by Tom Gramenz, rather than by Patrick Mölleken as in every other episode. This is especially noticeable because they don't even have the same hair color. Thommy doesn't appear in the opening credits until episode 2 despite a prominent role in the first episode, so this was presumably intended as just a temporary measure.
Pretty Little Liars has done this quite a few times, though most of the recasts happen if the character only appeared once. Some of the characters who change actors include Toby Cavanaugh who is played by a different actor in the pilot than in the rest of the series, Kate Randall was recast for season 2 after her only appearance in season 1, Mrs. DiLaurentis is recast in season 2 and played by a pretty different woman in the pilot, and Jason DiLaurentis changes actors in season 2 after having appeared several times in season 1 by not only a very different looking actor but he also seemed to get a personality change after a discovery about the character in late season 1. He is discovered to have used pot much to the surprise of the liars in season 1, but by season 2 the flashbacks make it appear that everyone knew he was a pothead and the real surprise was that he drankHe also becomes a pariah amongst his family by season 2 when in season 1 he seemed a lot more similar in personality to his half-sister Spencer Hastings (ie. he was mature enough to handle organizing her memorial service and was pressuring the police for answers).
Hannah Montana recast the annoying neighbor with the actor's identical twin brother. Most would only know if they checked the credits.
Bob Bell, Chicago's Bozo the Clown, retired after more than 20 years of playing the character. After a national talent search Joey D'Auria took over the role. This was covered extensively in local news outlets but on the show itself there was no indication that it was any but the same Bozo (albeit with very different voice and mannerisms).
Outsourced replaced Sarayu Rao with Noureen DeWulf as Rajeev's fiancee Vimi after two appearances.
Neely Capshaw of Baywatch was played by three actresses: Heather Campbell as a guest character, Gena Lee Nolin as a regular character, and finally by Jennifer Campbell for a few episodes in the ninth season.
The Swedish remake of Steptoe and Son, Albert och Herbert, was a major success after the first season, so a second season was soon planned only for it to be found out that Lennart Lundh, the actor for Herbert, had quit acting to become an antiquarian in Paris. Fortunately, a young actor named Tomas von Brömssen was found as a replacement.
The Walking Dead: As of the sixth season, Judith has been played by seven sets of twins. She also seems to be stuck in some kind of age time warp where she's perpetually six months old...for four years.
In Sharknado Aubrey Peeples played Claudia; as she was tied up with Nashville come Sharknado 3: Oh Hell No!, Claudia was played by Ryan Newman (who's younger than Peeples).
On The Odd Couple Felix's daughter Edna was played in different seasons by Pamelyn Ferdin and Doney Oatman, who, other than both being blonde, looked very different from each other.
Trinity in Trailerpark Boys is played by Jeanna Harrison, except for the first movie, in which she's played by Lydia Lawson-Baird.