The Amazing Race: The producers have a couple of personality types that they love casting Once a Season, such as "the young dating couple who bickers their way through the race" and "the quirky male friends team who swings back and forth between being fun to watch and being insufferable with their camera mugging". The most blatant specific examples, though, are Ken & Gerard (Season 3) who were bald, middle-aged and hilarously snarky fan favorites like Kevin & Drew (Season 1) and Uchenna & Joyce (Season 7) who were an amiable, married African-American couple just like Chip & Kim (Season 5) and even managed to pull off a similar underdog victory against a seemingly unbeatable and egotistical team.
Doyle is rather similar to Whistler, a character who appeared in the season two finale of Buffy the Vampire Slayer. Both are demons, both help Angel out, both serve (or served, in Doyle's case) as intermediaries for The Powers That Be, both are frequently sarcastic... Word of God in fact says Whistler was originally intended as Angel's sidekick, but schedule conflicts with the actor caused them to use Doyle instead. Which creates a certain amount of overlap with Suspiciously Similar Substitute. In "City of" Doyle even wears a hat similar to Whistler's iconic hat.
Izzerial ("Izzy") the Devil from the Circle of the Black Thorn, a very obvious one for Satan. Aside from the name, he's a red demon with a forked tail.
Marcus pointed out on-screen that how they are all similar to characters from Arthurian legend. Word of God is that this was meant to foreshadow the reappearance of Anna Sheridan. It worked to some degree, as Marcus' wondering aloud at the end who was supposed to be Morgan LeFay had people on Usenet opining that Anna Sheridan wasn't really dead.
One episode also features two comedians who are clear expies of Penn & Teller. Being played by Penn and Teller.
Beverly Hills 90210: Every character in this show has an almost perfect parallel character in the new 90210. Kelly is now Naomi, Dylan is Liam, and so on into infinity.
Bron|Broen: Saga Norén is so remarkably similar to Kathleen Mallory from Carol O'Connell's prose detective novels that it's hard to imagine there wasn't an influence. About the only difference between them is that Kathy is apparently asexual while Saga picks up random guys in bars for sex. (And then freaks them out by starting her laptop up and looking at autopsy photos as soon as they've finished.)
For another example, look at Gnarl from "Same Time, Same Place" and tell us he doesn't remind you of Gollum. They even have the same habit of referring to themselves in the third person.
Buffy, as a character, is largely based on Kitty Pryde, a character in X-Men. It's been theorized she was inspired by Regina and Samantha Belmont of Night of the Comet: blonde, Californian morons who find themselves battling the undead.
Lothos is one for Dracula because of his pale skin, style of clothing, aristocratic background and vampirism.
Cole is clearly an expy of Angel in Buffy. Reformed demon starts a love affair with female hero, then reverts to evil. Then good again. Then semi-evil (see season 2 Angel series). Aaron Spelling obviously agrees with the saying 'good writers borrow from other writers; great writers steal from them outright'.
The feuding Montana and Calloway families from season 6 are the Montague and Capulet families from Romeo and Juliet, complete with Star-Crossed LoversRichard Montana and Olivia Calloway.
Season 4 of Community has Reinhold, an expy of his brother, Juergen, the annoying German foosball player from Season 3.
Danger Man: Patrick McGoohan's character of John Drake on the two versions of the series (the second is also known as Secret Agent) has the same name on both shows but a different backstory, suggesting that the second version is an expy of the former. Then McGoohan went on to play the unnamed Number Six on The Prisoner, who is clearly an Expy of Drake.
Degrassi The Next Generation: J.T. and Toby are updated versions of Arthur and Yick from Degrassi Junior High, while Sean is an updated version of the earlier show's Rick. (Both Sean and Rick are Troubled, but Cute, but the similarities go further — both live with their adult brother, both had an edgy relationship with a social-activist girl, etc.)
Rick, in turn, is an expy of Griff on The Kids of Degrassi Street, who lived with his adult brother after his parents died. Wheels is also a partial expy of Griff, having been orphaned as well, having a nickname based on his last name, and being played by the same actor.
For that matter, Emma starts out as an updated Caitlin (Emma dates Sean, Caitlin dates Rick, both are social-activist types). Ashley, however, is a bit of a subversion—while both she and Steph ran for class president and were friends with socially awkward girls, Ashley, unlike Steph, based her campaign on honesty.
There's also a parallel between the later show's Rick and the earlier show's Claude in regards to their interactions with Emma/Caitlin—both were rejected and ended up dying as a result (Claude by a deliberate suicide, Rick by his own gun after being calmed down from shooting up the school).
Now that most of the cast were put on buses or just commuting, most of the characters introduced in seasons 7 and 8 are Expies filling in the roles the cast left open. Clare has Emma's strong morals, Alli is Manny except fiestier, Holly J fills in Paige's Alpha Bitch spot (except Holly J isn't as sociable) among other examples.
New character Declan Coyne is pretty similar to Gossip Girl's Chuck Bass, except Declan is just michevious and not nearly as contemptible.
Doctor Who: The last story of the sixth season featured the War Chief. He's an evil, megalomaniac Time Lord who dresses in a dark Nehru jacket, sports Facial Hair of Evil and knows the Doctor from their days on Gallifrey. He's extremely camp, has no concept of personal space and offers the Doctor a half-share in the universe. Fast forward to Season Eight, where we are introduced to a new regular villain who's an evil, megalomaniac Time Lord, dresses in a dark Nehru jacket, wears a Beard of Evil and— oh, you get the point. Fanon has even identified them as the same character.
Erst Stavro Blofeld has been an enduring influence on The Master; what with the Nehru jackets, the kitty-stroking in "Survival", the elaborate deaths for unwary henchmen, etc.
And in the new series, companions Amy Pond and Rory Williams share quite more than a few traits with Sally Sparrow and Larry Nightingale from "Blink", a story Steven Moffat wrote before taking over as the head writer.
Jack Harkness has a number of similarities to one of the Eighth Doctor's Doctor Who Magazine comic-strip companions, Fey Truscott-Sade, who like him is a morally-ambiguous secret agent with Extreme Omnisexual tendencies, who flirts with the Doctor a lot. The only major difference is that Fey is female, although very gender-ambiguous.
Colonel (later Brigadier) Lethbridge-Stewart resembles Colonel Breen from Quatermass And The Pit. So much so, that originally Julian Glover from the then-recent movie adaptation would have played him had the original actor not dropped out.
All the new series Doctors so far owe a great deal to one of the previous Doctors specifically, although with a twist, and the stories they are in are often quite different:
Christopher Eccleston's Doctor is a Darker and Edgier version of Tom Baker's - very obviously alien, defiant, lanky, oversized facial features and sudden toothy smiles, often quite rude to people, chaotic, strange and basing his perception of right and wrong on his instincts in all but the gravest of times. This fits as Tom Baker is the most iconic Doctor, associated with the show even by non-fans, and subverting his image indicated what the Re Tool was going to be like.
David Tennant is a Hotter and Sexier Peter Davison - glasses he doesn't need, easygoing, mostly appearing harmless but with a seriously dark streak, one of the most sensitive Doctors, a big planner and struggler with moral decisions, seems to long for a peaceful life, loves his companions enormously, considers himself bound to do what is right by his strict moral code. David Tennant even tells Davison this in a Comic Relief special, saying he based some of his own quirks on Davison because he is currently his favourite previous self.
Matt Smith is a Younger and Hipper Patrick Troughton - dotty old man, weird and hyperkinetic body language, willing to chat happily with everyone and everything including babies and animals, takes great pleasure in being very annoying. This was stated by Word of God.
Then again this is part of Whedon's Signature style, Xander also filled a role similar to the above two. In fact Whedon called Wash the Space Xander.
Topher's Affably Evil character was also a lot like the recurring character in Angel Season 5, Knox, although Word of God is that it was a tough call on whether to make Knox turn out to be evil, that wasn't decided until the story for the episode "Hole In The World" was fleshed out. It's still part of Whedon's style either way, as had Knox turned out to be basically good he then would be more like Wash.
Don't Trust the B---- in Apartment 23: Chloe is basically a human, female Roger (it should be noted that the creator of the former wrote for American Dad). Both characters even used foster children for their own personal gain.
Farscape: The fourth season villain Grayza has massive similarities, including a near-identical hairstyle and dress sense, to Blake's 7Big Bad Servalan. In the first season, Crais had lesser but still clear similarities to the Blake's 7 villain Travis, although the two characters became completely different after Crais's Hazy Feel Turn.
Father Ted creators Arthur Mathews and Graham Linehan typically have a trio of characters that fit similar archetypes. Compared to other series Black Books and The IT Crowd, there's the (flawed) sane one,note Ted, Fran, and Jen.the idiot,note Dougal, Manny, and Roy. and the unsociable one.note Father Jack — violent and alcoholic, Bernard — hates everyone, and Moss — socially awkward.
Firefly: This is an odd one, because the original characters never actually made it to screen without substantial revisions, but reading Joss Whedon's first draft script of Alien: Resurrection shows some definite parallels with the main characters of Whedon's later TV series Firefly. Both feature a crew of smuggler outlaws on a small, sturdy old ship (the Betty in Alien: Resurrection, and Serenity in Firefly), and some characters are written similarly as well: Johner and Jayne are quite similar even in the final film, Elgyn is written as quite similar to Mal, Zoe seems to be a composite of the original conceptions of Hillard and Christie.
Fresh Meat: Kingsley is the same character as Simon from The Inbetweeners. Both were played by the same actor and Fresh Meat could even plausibly follow on chronologically from The Inbetweeners.
Especially plausible because Kingsley never talks about his life before he became a university student. It's not implausible that he is Simon, and simply chooses to go by Kingsley because he wants to distance himself from his past life.
Glee: The cast of have many similarities to the cast of Ryan Murphy's other high school drama Popular, as shown by this article.
Also In-Universe, the new characters in Season 4 all have their counterpart in the first generation (this is often explicitly stated): Marley for Rachel, Jake for Puck, Kitty for Quinn, Ryder for Finn and Unique for Mercedes.
House: Considering how much the show was based on the Sherlock Holmes stories, clearly the expies are there. House is Sherlock, obviously, the Insufferable Genius with his Deadpan Snarker side. Wilson is Watson, the Straight Man to House's Wise Guy. Stretching it a little further, Dr. Cuddy is Inspector Lestrade, who used to do House's legwork and has the same "I hate you, but you're too valuable to get rid of" tone we see in Lestrade.
The Joe Schmo Show: Intentionally made its characters reality show archetypes as part of its premise. Gina "The Schemer" was based on Richard Hatch from the first season of Survivor. Hatch was inauspicious early on to the point of David Letterman turning him into a Butt Monkey, but it turned out he was Crazy-Prepared psychologically and physically (although overweight at the start of the show, he'd lost a substantial amount of weight in preparation) and played the game expertly and went on to win. Ironically, Gina was voted out at the end of the first Joe Schmo episode, and guess who she quoted verbatim in her parting speech.
The first season also included an extremely obnoxious character Steve Hutchinson, played by David Hornsby, who liked to be called "The Hutch" and was constantly picking on a gay Hispanic character called Kip. He was obviously based on The Real World's most famous season, Season 3, where an extremely obnoxious Narcissist who went by "The Puck" picked on the gay Hispanic man Pedro. Pedro had AIDS, which they obviously didn't replicate with Kip, but otherwise that conflict was obviously based on that season.
The second season had Ambrosia, who was quite clearly based on Omarosa from The Apprentice.
The LA Complex: Abby was originally planned to be Manny Santos. When they made the choice not to make a Spin-Off, she gained a new name but kept the same actress and the same background down to hometown and her boyfriend back home's of job.
Every episode of Law & Order: UK was based on a episode of the original series—episodes that Dick Wolf considered among his favorite and/or the best, and the characters were as well:
Snarky, world-weary, twice-divorced alcoholic Ronnie Brooks was obviously based on Lennie Briscoe.
Young, handsome, hot-tempered Matt Devlin based on Mike Logan, as was his replacement Sam Casey, but his replacement Joe Hawkins is based more on Ed Green.
Natalie Chandler = Anita Van Buren
James Steel= both Ben Stone and Jack Mc Coy, but his replacement Jacob Thorne appears to be solely based on Mc Coy.
George Castle and Henry Sharpe= Adam Schiff
Phyllis Gladstone=Danielle Melnick
The only two characters who aren't clearly based on original characters are Alesha Philips and Kate Barker, yet they still fall into the "pretty young woman" that became a staple of the original once Robinette left.
LOST: An expy of Mac (It's Always Sunny in Philadelphia) appeared in two episodes as a member of the Others; he was even played by Rob McElhenney. It waspure genius. The first time he appeared as just an extra who was knocked unconscious by Kate. The next time was his slight ascension in which he displayed very Mac-like qualities, such as his manner of speech when talking about the Smoke Monster and complaining that Kate didn't remember attacking him in his first appearance. Of course this being Lost and not Philly, he didn'tlast long.
Merlin: To the first series of Smallville: the superpowered teenager who can't reveal his secret (Merlin and Clark); his father figure who knows his secret (Gaius and Jonathan); his male best friend who will one day learn his secret (Pete and Arthur), his female best friend with UST (Gwen and Chloe); his future enemy pre-Face-Heel Turn (Morgana and Lex); said enemy's antagonistic father (Uther and Lionel). And later, his ally who knows his secret (Lancelot and Oliver) with a team of warriors (Knights of Camelot and the Justice League).
Queen Annis bears more than a passing resemblance to Boudicca, and there's some speculation that Princess Mithian was based on the more familiar characterization of Guinevere, being both high-born and in a (temporary) Arranged Marriage with King Arthur (the show's real Guinevere being a servant girl widely known as Gwen).
Though not strictly a character, the Mage Stone in To Kill The King is clearly The Philosopher's Stone, presumably changed in order to avoid comparisons with Harry Potter.
The Cup of Life is clearly the Holy Grail.
The Middle: Some people claim that the characters are like the characters of Malcolm in the Middle. Axl (awkward teenager who's not that smart) would be Reese, Brick (little kid who is a little bit too smart) would be Dewey, and so forth. Even the setting is similar (somewhere in the middle of suburbia).
Pretty Little Liars: Alison is an expy of Laura Palmer. Both are beautiful, popular high-school girls with dark secrets well beyond their years, both are Posthumous Characters remembered fondly by their towns despite their true Byronic Hero natures, and their passing leaves their friends with more questions than closure. Alison even has an FBI agent named Cooper (a woman, in this case) investigating her death, and she leaves behind a video that's very similar in content and plot-relevance to one left by Laura.
Saturday Night Live: The 1980-81 cast was intentionally comprised of actors meant to be reminiscent of the original Seventies cast. (Unfortunately, this gimmick ended up having a negative effect, particularly after the first sketch of the season was centered around it. The actors failed to live up to the comparisons in many ways.)
Denny Dillon = Gilda Radner - The 'cute' one.
Gilbert Gottfried = John Belushi and Harry Shearer - Although, Jean Doumanian wouldn't actually allow Gilbert to use his manic personality that would've fit the Belushi comparison, and the Shearer comparison is a complete fluke.
Gail Matthius = Laraine Newman - Most obvious in the first episode, where Gail appears as both the Update correspondent and a valley girl.
Eddie Murphy = Garrett Morris - A comparison Eddie resented bitterly.
Joe Piscopo = Dan Aykroyd - Even adopting Aykroyd's Tom Snyder impression and motormouthed pitchman character.
Ann Risley = Jane Curtin - Bizarrely, Ann is stated in the opening sketch to be similar to Gilda... which is completely wrong.
Charles Rocket = Chevy Chase and Bill Murray - Close enough to the latter, in fact, that Bill mentioned it in the episode he hosted that season.
The next cast (hired to replace most of the above) seemed to move away from the 'Seventies counterparts' idea, thankfully. For example, none of the original cast are particularly similar to either Robin Duke or Tim Kazurinsky.
Much of the current cast are expies:
Vanessa Bayer = Maya Rudolph
Nassim Pedrad = Amy Poehler
Andy Samberg = Adam Sandler (right down to near-identical names)
The show's purported star, Kirsten Wiig, is an expy of Carol Burnett, whose own sketch-comedy show paved the way for SNL.
In 2013 members of the comedy troupe Good Neighbor (performers Beck Bennett and Kyle Mooney and filmmaker Dave McCary) joined SNL and were very clearly intended to fill the void left after the members of The Lonely Island departed, including making short films (though they're very conspicuously NOT labeled as Digital Shorts). They also seem to be grooming Bennett to be an expy of Jason Sudeikis (versatile guy-next-door type).
After Phil Hartman left they hired Michael McKean to explicitly fill the "utility player who can do impressions, leads and supporting roles and is a little older than the rest of the cast" slot that Hartman left open. But McKean's strengths were different than Hartman's, he seemed out of place and a bit uncomfortable in sketches, and he only lasted one year (the much-maligned 1994-95 season).
Saved By The Bell The New Class: Most of the original cast were basically the old class with different actors. Apparently it didn't go over well, because the cast was largely overhauled early on.
Scrubs: Some of the new interns in season 8 seem to be Expies of the main cast.
Katie Collins is explicitly nicknamed "Mini Elliot" (and is even caught making out with another intern in a pink bra in one scene, similar to what often happens to Elliot, who often takes her shirt off for one reason or another and is always wearing a different coloured bra every time).
Derek Hill has some similarities to Turk, but Turk realizes that he acts in a serious and arrogant manner.
Howie Geller is a mixture of JD, Doug and The Todd.
Dr. Sonja "Sunny" Dey is almost exactly like the short Indian girl with the squeaky voice, only taller.
Nurse Roberts friggin dies... and then the actress Aloma Wright comes back like five episodes later to play Nurse "Shirley". J.D. Lampshades this by calling her Lavern-again. She is never seen after this.
Tess Mercer, in her first two appearances, was referred to as both "an obscure regional VP" (unfit for her job of taking over for Lex Luthor) and a "pitbull in Prada." The first was said to her while they were up in the Arctic. The second, after she had firmly assumed control of her bald boss's former position. That's right, it's Sarah Palin. Of course, she's intended as a fusion of Mercy Graves and Miss Teschmacher (tending much more toward Mercy.)
The episode "Warrior", turned the in-universe fictional Warrior Angel into a Captain Marvel Expy.
There are some sharp similarities between Green Arrow's characterization and relationship with Clark, and that of Batman. Throw in the fact that The Dark Knight Saga likely meant the writers couldn't use Bruce, and that makes a lot of sense all of a sudden.
Appropriate, given that initially Green Arrow was very much the poor man's Batman in the comics, with his earliest stories featuring Speedy as a blatant Expy of Robin, as well as an Arrow-Mobile and even an "Arrow Cave."
Stargate Atlantis: Rodney McKay is basically Gary Meyers from the original Stargate with a different profession. They even look similar.
Star Trek: Voyager: The creators wanted to bring back Nicholas Locarno, a character from a Next Generation episode. However, the character had been created by the writer of that episode and not by TNG's creators or executive producers (as was the case for recurring characters such as O'Brien or Worf, which could be reused). Because of this, the creators of Voyager thought they'd have to pay royalties to the writer of that episode every time they used the character, and that led them to create a new character similar to Locarno's named Tom Paris with a similar back story and who would be played by the same actor. To cover the transparent change, the creators said that they decided Locarno was irredeemable due to his actions in the episode, but Tom Paris's actions (which were more like Wesley's in the original episode) were less culpable. note However, the only difference between Locarno's actions and Paris's, as heard onscreen, is that three died in the Paris version instead of one as in the Locarno version! Interestingly, many years later a California court ruled that producers in a similar situation didn't have to pay royalties to a writer who created a character; had the producers of Voyager chosen to take the matter to court, they might have been cleared to use the character Locarno.
B'Elanna was supposed to be Ro Laren. Apparently they wanted her to be on Deep Space Nine (later replaced with Kira) and then tried again with Voyager (later replaced with B'Elanna) but the actress kept saying no.
And Kira on Deep Space Nine was initially supposed to be played by Michelle Forbes (Ro Laren), but she declined to focus on her film career. We all know how that worked out.
Also, The Next Generation's Taurik becomes Voyager's Vorik, and keeps same actor. The Expanded Universe says they're twins.
Gul Macet from TNG's "The Wounded" gets a shave and becomes Gul Dukat from DS9. The Expanded Universe makes them cousins.
Subcommander Taris of TNG's "Contagion" has become Commander Toreth by the time of the much later episode "Face of the Enemy."
The official Next Generation interactive VCR board game had Robert O'Reilly playing a Klingon terrorist named Kavok, an Expy of his usual character Gowron.
Probably coincidental given that the Doctor hadn't properly developed many of those characteristics at the time that "Assignment Earth" was broadcast, and Doctor Who didn't have much of a US profile at the time anyway. There's rather more justification for the allegations you'll frequently hear from Doctor Who fans that the Borg are Cyberman Expies if not full-blown Captains Ersatz.
Interestingly, you also hear it the other way around. Cybermen came first, but the revived series has them much more Borg-like in behavior than the old-school ones. One episode even casts all pretense aside and has a Cyberman say "You Will Be Assimilated" instead of the usual "You will be/prepare to be upgraded." By "Nightmare in Silver," the Cybermen's latest upgrade has them able to share newly developed countermeasures across the whole "cyberiad," resulting in "shoot the Borg with a new weapon; it works twice but the third is able to No Sell it" scenes being replicated with the Cybermen.
Supernatural: Sam Winchester is modelled after Luke Skywalker and Dean Winchester is modelled after Han Solo from Star Wars.
The Trickster is a miscievous Reality Warper who enjoys screwing with the heroes while also trying to teach them a lesson and sometimes outright helping them. Essentially he's Q transplanted from the sci-fi setting of Star Trek: The Next Generation into a dark fantasy universe.
Terra Nova: Nathaniel Taylor is Colonel Miles Quaritch from Avatar, down to being played by Stephen Lang. Being nicer doesn't make him any less badass.
The Tick couldn't use the animated characters Die Fladermaus and American Maid, so they were replaced with expies Batmanuel and Captain Liberty.
Davies seems to have brought in a lot of influences from earlier works. Gwen bears a resemblance to Rose in her role. Captain Jack comes across as a hybrid of the Doctor and Stuart from Queer as Folk, while Ianto became more and more like Vince, especially in his relationship to Jack, as the series progressed.
Two and a Half Men: Judith is a clear Expy of Lillith from Frasier. She's a vindictive ex-wife, is quite neurotic, and speaks in a very similar manner.
Unhappily Ever After: The main characters were obvious expies of those in Married... with Children. The main difference was that UEA replaced the family dog with a puppet. Since the two shows were created by the same people, they basically sold the same idea to two different networks.
The Vampire Diaries: April Young has a few things with Season 1 Caroline, right down to winning Miss Mystic Falls like her.
Wings: Joe, Brian and Helen's representations during the first season are quite similar to that of Chip, Dale and Gadget from Chip n' Dale's Rescue Rangers (which premiered a couple of years before "Wings"). Joe and Chip were the smart, responsible pilots with the cool jackets, Brian and Dale were the goofy, fun-loving brothers who wore Hawaiian shirts, and Helen and Gadget were the cute blondes that the brothers fought over.
The Alex and Mason relationship is very much like another relationship - and the episode where Alex met Mason's family (all of whom wanted to eat her) makes the entire relationship (after Wizards Vs. Werewolves) seem like a bad rehash of Twilight.
The X-Files: Only appeared in one episode of the series (two if you count Millennium), but thriller novelist Jose Chung is a double expy of Truman Capote and series adviser Jack Cohen.
Bud Spencer (real name Carlo Pedersoli) currently stars in an Italian TV series where he plays a former police commissioner with a passion for cooking, who now owns and runs a restaurant in Ischia, an island near Naples. Given that he played Neapolitan commissioner "Piedone" Rizzo in four movies during the '70s, this latest character may be Rizzo after he retired from active duty.