YMMV / Castle

  • Actor Shipping:
    • It's called Stanathan. With many, many YouTube videos. It was strongest in the first four seasons, but appears to have subsided heavily since then, which is ironically around the time when their characters became a couple.
    • The ship is now dead as a doornail: Stana Katic married her boyfriend Kris Brkljac in April 2015, and ABC announced in April 2016 she would be leaving the show after Season 8 (a month after this, they then announced the show was cancelled, full stop). This seems to confirm a lot of behind-the-scenes rumors that Katic and Fillion were not getting along with each other and have not been for at least several seasons, possibly going as far back as Season 4.
  • Anvilicious:
    • Beckett on deficit spending, in the episode "Close Encounters of the Murderous Kind". Lampshaded, however, in that Castle, taken aback by Beckett's in-depth and forthright discussion of her views on this, has a classic "where the hell did that come from?!" moment.
    • "Suicide Squeeze" hammers the 'Castro's Cuba is terrible' message home a bit too hard.
    • "Countdown" takes this to a bit of an extreme level, where somehow the fact that a bomb will detonate somewhere in NYC in the next twelve hours or so doesn't keep people from sitting around, waxing philosophic about all the different aspects of terrorism.
    • In "To Live And Die In L.A", the ending of the letter Royce sends Beckett, spelling out the fact that she has feelings for Castle she's denying, is a bit on-the-nose. Then again, this is Beckett we're dealing with here.
    • Beckett talks deficit spending again in "Linchpin."
    • Subverted in "Till Death Us Do Part" with Beckett's comment about the importance of keeping secrets in a relationship, as it's so clearly contradicted by Ryan and Jenny's complete honesty about who Jenny's slept with as well as the secrets on both sides that are getting in the way of her having a relationship with Castle.
  • Arc Fatigue: Many viewers are becoming tired of the LockSat narrative, which has been dogging Season 8 from start to finish. It's unlike the show's formula to have a major villain be ever-present throughout many consecutive episodes (yet never seen) and affecting the protagonist's stories and decisions on a constant basis - in contrast to other key plots, which were in the background if not focused on). Worse, though, is it also implemented a hugely unnecessary Retcon that revealed Senator Bracken was working for someone else, which basically brought back the Beckett's Mother Arc over a year after it was definitively resolved with Bracken's arrest, and the unpopular decisions that led to Season 8 being so unpopular with viewers.
  • Broken Base: Fandom's starting to show signs of this - those who dislike season four vs those who just enjoy the show for escapist fantasy.
    • Season five. Castle and Beckett are now together, and some fans are annoyed with the way it's being treated - it's been compared to high school shenanigans. The finale, where Castle proposes to Beckett, has caused an even larger divide.
    • Another base is over Alexis, with those who think she's being a spoiled brat over her divisions with Castle (particularly with Pi) versus people who think she's acting like a perfectly normal daughter rebelling against her playboy father.
    • Season 8A. The decision to split temporarily Castle and Beckett not even a year after their marriage in order to continue the big 'mystery' storyline has been polarizing to say the least.
    • The finale. Not a few people think it was done in a rush after it was clear there would not be a ninth season.
  • Complete Monster:
    • Scott Dunn from the season 2 two-parter "Tick, Tick, Tick…"/"Boom!" was a Serial Killer who, prior to the events of the episodes, killed prostitutes, framed another man, hung him and made his death look like a suicide. Later on, he kills a businessman just to live off his identity. When he becomes obsessed with Kate Beckett through Nikki Heat, he learns about a man named Ben Conrad and then proceeds to hold him hostage in his own apartment. Pretending to be Conrad, Dunn murders three people seemingly at random, each one connected to Conrad's dead dog, and each time calls Beckett to taunt her. He takes the body of the third victim and leaves her at Beckett’s apartment as another threat to her. When shooting the third victim, Dunn didn’t kill her right away, letting her bleed out. Dunn then kills Conrad and stages him as shooting himself to frame him as the killer. Dunn later sneaks into Beckett's apartment, leaves a bomb and then sets it off while she's there. Enraged when Beckett just manages to survive survives, Dunn calls her to vent and while he does, kills a random woman out of anger. Dunn's revealed to have privately written about his killings to immortalize and take pride in them. When his identity is uncovered, Dunn takes FBI agent Jordan Shaw hostage, threatening to kill her unless Beckett gives herself up to him. He leads the FBI team astray to the wrong building where he plans to blow them up with another bomb. When Beckett tricks him into thinking they saw through his ruse and he failed, he angrily lashes out by attacking and nearly succeeding in shooting her.
    • Dr. Van Holtzman from the season 7 finale "Hollander's Woods" is a masked Serial Killer who has been active for over thirty years. With at least nine victims to his name, Holtzman abducts young woman whom he believes won't be missed, carves crosses into their faces, then cuts their throats. When an eleven-year-old Richard Castle comes across Holtzman disposing the body of one of his victims, Holtzman threatened to kill him if he told anyone what he saw, only sparing him to avoid drawing attention to his other crimes. Years later, when the adult Castle and Detective Kate Beckett investigate another of Holtzman's murders, Holtzman attempts to frame one of his mentally ill patients for the killings. While searching the barnhouse where Holtzman murdered his victims, Castle discovers a scrapbook filled with pictures of Holtzman's victims. When Holtzman arrives, he expresses regret for not having killed Castle as a child, then promises to kill both Castle and Beckett before attacking Castle and trying to slowly cut his throat. Taking pride in his crimes and considering his mask to be his real face, Holtzman is a vicious killer who left an impact on Castle for his entire life, and who stands out in a normally lighthearted series.
  • Crazy Awesome: Castle's MO. Remind you of anyone?
  • Critical Research Failure: Usually known for aversions, sometimes to pleased reactions from the subcultures they touch on, but there are misses.
    • Season 2 episode 5, "When the Bough Breaks" and Czech Republic, its language, and its sweets.
    • Season 4 episode "The Limey" featured an English police detective (played by Australian actor Brett Tucker pulling a deeply unconvincing Fake Brit accent) who was introduced as being from 'Scotland Yard'; his ID card said in big letters 'SCOTLAND YARD' and featured an elaborate multi-coloured crest incorporating, among various heraldic elements, a fleur-de-lys, which is normally associated with either France or Quebec. 'Scotland Yard' is not the name of any British police organisation but the nickname for London's Metropolitan Police Service, which has an entirely different logo (featuring a lion, a unicorn and a portcullis, among other things, but not a fleur-de-lys), and Met Police ID cards generally have the words 'Metropolitan Police' on them somewhere. To viewers in the UK, it was a bit like somebody being introduced as a Wall Street lawyer and then producing a business card giving the name of the firm as 'Wall Street'.
    • Season 5 episode "Scared to Death" claims that the victims were 'scared to death', with no marks on their bodies. At the end they are found to have been killed by a modified taser delivering a shock big enough to cause an instant heart attack. Normal taser's already leave very noticeable burns when used, a police Medical Examiner would most certainly recognize them, and a higher yield one would likely leave a significantly more pronounced burn when used.
  • Die for Our Ship:
    • Detective Demming upped the ante by kissing Beckett in "Overkill", thus securing his status as arch nemesis of all Castle/Beckett shippers. "DEMMIIIIIIIIIIING!" * shakes fist*
    • As of the end of Season Two Beckett broke up with Demming... just in time for Castle and his ex-wife Gina to start hooking up again. Gina's got her work cut out for her, stepping into Demming's shoes.
    • Towards the end of "Punked," Beckett appears with a new beau named Josh. The fan hate for this particular character goes Up to Eleven as of "Countdown." It came to a head in "Rise", when Josh accused Castle of getting her shot. Cut to three months later, and she's broken up with him, too.
    • Inverted to some degree with "The Limey", however, where both Castle and Beckett seem to get (presumably) temporary new Love Interests in flight attendant Jacinda and British cop Colin... except most of the fan ire around the episodes seems to be directed primarily at Castle and Beckett themselves, mainly for once again refusing to just have a sensible, adult conversation about their issues and relationship and instead dicking about around the subject with other people.
    • It only took the promo for "The Squab and the Quail" for fans to start wishing this upon Eric Vaughn, the genius billionaire inventor whom Beckett is assigned to protect and who kisses her at one point. After approximately two seconds of footage, he has apparently skyrocketed past even Josh as the most hated character in fandom. Considering that Josh is blamed by this same fandom for everything bad everytime (see Memetic Mutation), this is saying something.
    • Much like the Broken Base above, Alexis gets some hate for this, as well, apparently because her "bratty antics" take away from "Caskett time". Also, some think she doesn't like Beckett for some reason.
    • New Season 8 character Hayley Shipton drew suspicion early for possibly breaking up Caskett, but despite her now aiding Castle's PI firm, it doesn't seem like she has any interest in Castle romantically.
  • Double Standard:
    • The show is pretty good at making Beckett seem like the wronged party when it's her who's either overreacting or done something wrong. When Beckett lies to him about her job interview in D.C. the universe makes it look like Castle should have supported her upon finding out while his reaction is more than justified.
    • Ryan end Esposito, both detectives for years, seem Overshadowed by Awesome whenever Beckett is around. The show seems to think women can never be wrong.
  • Ear Worm:
    • The show's theme tune deserves a mention here.
    • The victim's eventual-murder-solving last song from "Famous Last Words". And they play it constantly throughout the episode. Auuuugh.
    • Get on the Floor, from "Lucky Stiff."
      • In-Universe, too, since Beckett is later seen trying to do an acoustic guitar version of the track.
    • The ringtone from "Nanny McDead".
  • Ensemble Dark Horse:
    • Lanie the Medical Examiner seems to be going this way. As of season two, she's been showing up more with bigger lines that aren't strictly about the case of the week. But then again, she also gets some of the best lines and could probably match wits with Castle so it's understandable. Fellow Medical Examiner Perlmutter gets some great snarks in on Castle, as well.
    • Detectives Ryan and Esposito have ended up becoming quite popular with the fans to the point of almost getting as much screen time as Castle and Beckett, but the charmingly Adorkable Ryan in particular might fit this trope most — he wasn't even supposed to be in the series initially, and was a relatively last-minute addition after test audiences didn't respond well to the detective who was initially supposed to take his place. He even has a Character Blog on ABC.com.
    • Captain Montgomery most definitely. Whenever he shows up, one can be certain he'll do or say something awesome. His death at the end of "Knockout" was no different and you can bet the tears flowed like rain.
    • West Side Wally in season four. He first showed up in "The Blue Butterfly," but made a reappearance in "47 Seconds." Lampshaded by Esposito.
    Esposito West Side Wally, back by popular demand.
  • Even the Girls Want Her:
    • Many of the girl fans' reaction to Kate Beckett.
    • This promo.
  • Fanon Discontinuity: The Season 7 finale was such a heartwarming sendoff, a lot of fans are making that their series finale (and ignoring the events of Season 8, with Castle and Beckett broken up and Alexis in the PI business with Castle.)
  • Fridge Brilliance:
    • In a rare case of this trope being taken literally, this is lampshaded occasionally by Castle and Alexis. In several episodes ("A Chill Goes Through Her Veins" and "A Deadly Affair", for example), facing logical puzzles or romantic dilemmas, they open the refrigerator and hang mournfully on the door, staring inside. Castle at one point comments, "What is it about the refrigerator? Is it the cold? The light? Or some combination of the two?"
    • In "Suicide Squeeze", the wife's victim thought he was having an affair with a woman that appeared in a photograph with him, who turned out to be the victim's daughter (the aforementioned 17-year-old). Given that she looked like a short adult, is it too outlandish that the wife thought the girl was her husband's lover? One of the few cases where Dawson Casting actually works!
  • Growing the Beard: Although the series was well-received in seasons one and two, putting Castle and Beckett together in season five appears to have given the show a critical and audience appreciation shot-in-the-arm after the Seasonal Rot of seasons 3 and 4 discussed below. Even the cast and crew seem just a bit more enthusiastic about the show now.
  • Harsher in Hindsight: Not so much harsher but sadder in that after the events of "Knockout", everyone knows exactly why Montgomery is so lenient with Beckett.
    • The Season 3 episode where Castle and Beckett get locked in a freezer. Beckett at one point remarks, that she always thought, as a detective, she'd die from a bullet. Guess what happens to her in the Season 3 finale? Okay, she didn't die from it, but that's pretty spooky.
    • In Season 7's "Meme Is Murder", Beckett laments about Internet trolls and bullies a hiding behind a username, in actuality, it was recently revealed that star Stana Katic and her family were the targets of Internet trolls as far back as October 2015. In a way art imitated life.
  • Hilarious in Hindsight:
    • In the pilot, at Castle's poker game after the premiere of the final Derrick Storm novel, James Patterson quips, "You certainly don't see me killing off Alex Cross." A few months later, he's advertising his next Cross book by saying "Buy this book, or I'm gonna have to kill Alex Cross."
    • In "Hunt" James Brolin turns up as Castle's long-absent father. Just over a week later, he turned up on Community as Jeff's long-absent father.
    • In Season 6's "Room 147", when Castle tries to make one of his theories, Beckett jokingly suggests that it has to do with alternate universes - which Castle regards as crazy. Come Season 7's "The Time Of Our Lives", and Castle appears in an Alternate Universe where he never met Beckett.
    • The actress who plays Nikki Heat (in-universe) said she lived for a month in a crawlspace for a role. Who would make a movie about a crawlspace?
  • Ho Yay: Ryan and Esposito. Oh so very much.
    • In "Den of Thieves", the word 'partner' is used repeatedly in questionable context.
    • Also in the same episode: "Where's Esposito? WHERE'S ESPOSITO?
    • In "Lucky Stiff" Ryan reveals that he plays Esposito's lottery numbers, so it wouldn't be awkward if one of them won. Uhm yeah...
      • Even moreso because Esposito's numbers are the dates of his firsts - as in, his first time in combat and the first time he had sex.
    • Castle to Esposito about Ryan when Ryan's girlfriend calls him yet again.
    Castle: Don't worry, he still loves you.
    Beckett: When I'm not here, do you guys braid each other's hair and discuss who's your favourite Jonas brother?
    Esposito: No... but it's Nick.
    Ryan: Absolutely Nick.
    • Esposito throwing Ryan up against a wall in "Knockout", after finding out that Captain Montgomery was involved in Johanna Beckett's murder. And the heads of a thousand Slash Fic writers exploded...
    • It gets better in "Dance With Death", when a (keep in mind, married for seven episodes) Ryan pretty much insists Esposito wear his wedding ring when interviewing suspects at a strip club... to see if strippers will flirt with him even if he's not taken. The scene is set up to look like a proposal, which isn't even mentioning the subtext that Espo gets a date because of the ring... and later, can't take it off because his finger's too big and needs Beckett's hand cream. Ryan panicked. Slashers squealed.
    • The best thing about the Ho Yay here is that Esposito and Ryan pretty much acknowledge the fact that it's there and just roll with it.
    • Between Castle and his old high school friend Damian in "The Last Nail." Teenage boy sent off to a boarding school, gets homesick, and gets comforted by an older student.
    • In "Probable Cause", Esposito assures Beckett that she's not alone in worrying over Castle's situation as the prime suspect of their current murder investigation.
    Esposito: I know how you feel about the guy. I love him, too.
    • In seasons 6's episode "A Murder is Forever", the victim of a week is a renown relationship therapist with a best-seller on relationships, and after having read it Ryan refers to it... but in the context of his relationship with Esposito, not his wife.
    • In "Under Fire", with Ryan and Esposito trapped in a burning building and Ryan's wife going into labor, they manage to contact the crew, and Jenny asks her husband what to name the baby. His response for a boy's name is "Javier". Even Espo criticizes that choice. Luckily for both of them it's a girl.
    • In the Season 4 blooper reel, Adam Baldwin grabs Nathan Fillion's butt. He responds by swatting his hand away and saying, "Later."
      • Several seconds later, the two (almost) kiss.
    • Female example: The killer in "The Mistress Always Spanks Twice" is the victim's female roommate, whose Motive Rant for killing is loaded with Les Yay with a Psycho Lesbian twist. Add in the fact that the victim once compared her to a dominatrix...
      • The female plastic surgeon in "Disciple" is absolutely fascinated by Beckett's "perfect face" and takes every opportunity to invite Beckett to come in and have some work done. Gets far, far creepier once it turns out it is extremely probable she was the real mastermind behind the killings and picked up all of 3XK's methods by dint of being his lover.
    • In the eighth season, Hayley and Alexis are drinking scotch in the PI office on a stormy night, wearing very nice dresses (at the same time Castle and Beckett are having a date night at home).
      Hayley: Looks like we're going to be late. Frankly, I'm in no mood to leave this party thanks to your father's excellent taste in scotch and daughters.
  • Internet Backdraft: It was announced that Stana Katic and Tamala Jones were cut from the proposed Season 9 for budget reasons. Needless to say, the fandom was ticked that the show's leading lady had been cut and coupled with the subpar Season 8, many are hoping the show doesn't get renewed so it can end on a high note. As it turns out there will be no Season 9, so the point is moot.
  • Jumping the Shark: Castle and Beckett's separation in the first half of Season 8 has been widely viewed as being one of these.
  • Left Hanging: "Disciple" ends with Beckett moved to tears after hearing a recording that 3XK left behind for them to find before his protegé disappeared. It has yet to be revealed what the song means to her although, it could just be the prospect that 3XK will return.
    • In Resurrection, it is revealed that Beckett knew the song meant she would be meeting Neeman again (and the 3XK, too).
  • Like You Would Really Do It:
    • At the end of "Tick, Tick, Tick" it looks like the villain of the two-part episode has blown up Beckett in her apartment. Of course she wasn't.
    • The trailer for season 3 shows the cops busting in and finding Castle over a dead body holding a gun. Clearly he did it and will be sent to jail for the rest of his life.
    • "3xk" has the -real- climatic scene involve a serial killer with Castle at his mercy. The scene cuts abruptly after the killer threatens Castle. Of course, Castle isn't killed but, at least in the killer's and Castle's mind, that may be a Fate Worse Than Death.
    • "Setup" / "Countdown" has a triple-whammy:
      • Castle and Beckett encounter the remnants of a highly radioactive device removed from a storage locker.
      • Castle and Beckett are locked in a freezer.
      • Castle and Beckett find themselves face-to-face with a dirty bomb counting down to zero. Obviously, it will explode, killing them and irradiating a good chunk of downtown Manhattan and its population, and they will not be able to do anything to prevent this. And if you believe any of the above spoilers, there is an excellent bridge property in Brooklyn for sale at a very generous price...
    • "Knockout" ends with Beckett shot and lying in Castle's arms, during which he finally whispers that he loves her. The entire fandom is sure she's not going to die, but the repercussions of the gunshot are the real issue.
    • "Probable Cause": It was highly unlikely that the main character of the series would be revealed to be a sadistic murderer who would be sentenced to prison six episodes in to the season. Slightly (but not much) more in-doubt, however, was the question of whether he had been cheating on Beckett with the victim.
    • "Valkyrie". Castle has been exposed to an aerosolised biochemical agent giving him one day left to live. Obviously, he will die in the second episode of the series, leaving Beckett without a fiance and the series without a main character.
    • The very end of "For Better Or Worse": Yeah, sure, you're gonna kill off the title character by running him off the road in a fiery conflagration. We all believe that one.
  • Magnificent Bastard: 3XK! Dude walked into a damn police station to taunt Castle. Stole all of his evidence. Walked into a police station again just to taunt Castle again. Faked his death how many times? He's he only bad guy to consistently get away from Castel and Beckett, and he does it without wealth and power.
  • Memetic Mutation: Due to his incessant cockblocking in Season 3, Josh Davidson has earned the reputation on Tumblr of being blamed for anything negative that happens in the fandom or the show, from the cast not winning awards to problems on the show itself. It is almost always capped with the following picture.
    • In-universe, there's Johnny Vong's commercial, which Castle and Esposito recite.
  • Moral Event Horizon: You can sympathize with the motives, if not the actions, of the terrorists in "Countdown" embittered soldiers who feel abandoned, betrayed and ignored by their country and their government, but they kidnap a mother and her baby (the husband and father of whom they'd already murdered), hold the baby hostage, all but threaten to kill her and force the mother to drive a truck carrying a dirty bomb into the city, which will ultimately frame her as the terrorist when it explodes.
  • Narrowed It Down to the Guy I Recognize: The show appears to take delight in zig-zagging furiously on this trope:
    • "Inventing the Girl": Julian Sands didn't do it.
    • "When the Bough Breaks": Reed Diamond did it.
    • "Little Girl Lost": Francis Capra, AKA Weevil, and Judy Reyes, AKA Carla Espinosa. Capra's a red herring, but Reyes isn't.
    • "Kill the Messenger": Gregg Henry pops up. Anyone savvy enough to know about this trope went "Oh. Oh well." Subverted.
    • Ray Wise in 2x15, "Suicide Squeeze". Played straight.
    • "One Man's Trash": features DB Woodside, 24's Wayne Palmer and Buffy the Vampire Slayer's Principal Wood, as well as Perrin "Mrs. Ari Gold" Reeves and Abigail "Miss Blah-blah Farrell" Spencer. Subverted for the women, not so much for the guy.
    • Played with like a kitten's ball of string and averted in "The Mistress Always Spanks Twice". Lesse, the deceased was a post-grad who had Lane Kim and Brian Krakow vying for the same award, so it must've been one of them, right? She also went undercover as a dominatrix in an S&M club whose proprietor is Dina Meyer, so maybe it's her? Nope: it was her roommate, who was played by a relatively unknown actress.
    • "Wrapped Up in Death", Navi Rawat (AKA Amita from NUMB3RS), Erick Avari (crazy Dr. Bey from The Mummy) and Currie Graham (from Desperate Housewives, among others). Currie Graham did it. Currie Graham ALWAYS is the murderer, unless he's a series regular. No exceptions.
    • "The Late Shaft" averts this by salting the suspects with enough B and C-list celebrities for a VH-1 reality show. Tom Bergeron played the big late-night talk show host victim; Fred Willard played his feisty sidekick, Beth Broderick played his first wife, Bill Bellamy played his heir apparent, Dan Cortese played the network president, Kelly Carlson played another guest who hooks up with Castle, and even French Stewart played a skeevy guy who did business with Bergeron. Fred Willard dood it.
    • Mitch Pileggi a.k.a A.D Walter Skinner turns up in "A Deadly Game" as a hardened spy / assassin. Hilariously subverted; turns out he's just some hapless schmuck on a spy vacation who thinks that this is all part of the game. Once he realizes he's in "real jail", he bursts into tears.
    • Muse Watson aka Mike Franks in "Punked". Didn't do it.
    • "Close Encounters of the Murderous Kind" has Lyle Lovett and Bishop. The killer was someone else.
    • "One Life to Lose" features All My Children regulars Rebecca Budig and Cameron Mathison, Jane Seymour, David Eigenberg, Corbin Bernsen, and Tina Majorino. That last one did it.
    • "Head Case" features Adam Davies (suspicious but didn't do it), April O'Neill (did it and then herself), Richard "Dickless" Thornburg (a subverted Corrupt Corporate Executive), and Yinsen (stole the victim's head, but with justifiable reason).
    • In "Demons": Has Frederic Lehne ever played a good guy?
    • In "Blue Butterfly": Mark Pellegrino, who has played Satan of all villains, appears as Tom Dempsey, a mobster in 40s and also his grandson Tom Dempsey III. Turns out that he was innocent of the murders in both cases. Infact, the grandson was a Nice Guy.
    • "Dreamworld" guest-stars Warren Christie — Cameron Hicks from Alphas. Guess who's the killer.
    • Annie Wersching and William Mapother show up in "Disciple". Mapother's character cops to the killing, but it's Wersching's character who is the titular disciple... to 3XK.
    • In "Hong Kong Hustle", we get not one, but two Star Trek alums in Linda Park (Hoshi Sato) and Rosalind Chao (Keiko O'Brien). Park's character is a good guy. Chao's character didn't do the crime, but her illicit trafficking business set it up.
  • Nightmare Fuel
  • One-Scene Wonder: Several witnesses, suspects, and other minor characters have their moments.
    • The old guy in "Nanny McDead" who — when Castle and Beckett conclude that he couldn't have been the one that the victim wanted to have sex with — shouts after them, "Seventy-seven ain't beyond the realm of possibility, you know!"
    • Introduced in "Punked", Ashley, Alexis' boyfriend, is accidentally [Twerp Sweated by Castle in what was, for a while, his only on-screen appearance.
    • Vulcan Simmons, a Smug Snake suspect in "Knockdown." He doesn't show up again until season 6, when he's shown to be running a drug operation to fund Senator Bracken's campaign for President. Then he appears in "Veritas", as part of an elaborate frame job meant to take Beckett out once and for all.
    • In "The Final Nail", a carpenter with an Eastern European accent that gets Beckett to accidentally mimic his accent.
    • Westside Wally, a homeless guy who insists on being called "Westside", appearing in "The Blue Butterfly". He returns in the episode "47 Seconds", reintroduced by Esposito:
    Esposito: Westside Wally. Back by popular demand.
    • Dr. Barker, the somewhat nutty dog doctor-slash-dog whisperer in "An Embarrassment of Bitches". It doesn't hurt that she's played by the always utterly charming Nana Visitor.
    • Gene Simmons was hilariously laconic and jaded: "Yeah, yeah, from Kiss. Yeah, yeah, with the tongue."
    • "Overkill" has two within about five minutes of each other — Benny, a charmingly sleazy and hungover motel clerk, and Rebecca, a very weepy lab technician with almost indecipherable "cry talk".
  • Or Was It a Dream?: The alternate universe in "Time of our Lives". Everything Castle experienced in the alternate universe could have been extrapolated from what he already knew except the fact that Beckett once stood in line for an hour to have him sign a Derrick Storm book. Only Will Sorensen knew that - and Sorensen was referenced at the beginning of the episode, just to remind us.
    • The beauty of this is, of course, that Castle still doesn't know it's actually true, so it's only the viewers who are left wondering whether the AU could actually have been real in-universe.
  • Paranoia Fuel: The cloaking technology used in Clear and Present Danger allowed the killer to be completely invisible which means they could be anywhere and everywhere.
  • Rescued from the Scrappy Heap: Gates seems to have shaken off the hatred piled upon her when she arrived, especially now that she's been revealed to have her own quirks and Hidden Depths. It helps that she's dialed back the open hostility towards Castle a bit, while still keeping the snarkiness towards him.
  • Romantic Plot Tumor: Whether you like it or not, the Castle/Beckett relationship is and always has been a central driving engine of the show so isn't one of these. The 'significant others' plot arcs of the latter part of season two and season three, however, are generally disliked by the fans because they break up Castle and Beckett (the chemistry between the two generally being considered one of the show's great strengths) and shove them with other people in a predictable and angsty way that seems to have little point other than to act as a 'roadblock' that kills time and prevents them from getting together.
  • Ron the Death Eater: If he shows up in fanfic, expect Josh Davidson to be presented as, at minimum, a pretty big tool. Granted, we didn't learn a lot about him and one of his few appearances involved punching Castle in the face (albeit after having just operated on his girlfriend, who had just been shot), and he does come off as a being a bit smarmy, but he's still suggested to be a devoted doctor and an all-round decent guy.
  • The Scrappy:
    • Pi, Alexis's boyfriend in Season 6, who is basically what you get when you cross a Cloudcuckoolander and a Granola Guy together. Few fans have any kind things to say about him.
    • Josh Davidson is not popular with anyone. At all.
    • Vikram Singh in Season 8, mostly for being part of Beckett's team in her quest to take down Locksat (which led to her pushing herself away from Castle supposedly for his own safety.)
    • Hayley Shipton also from Season 8. Because she's a PI and not tied down by laws, she's able to make the entire cast look incompetent and inefficient in comparison - including Beckett and Castle.
  • Seasonal Rot:
    • The third and particularly fourth seasons have come in for some criticism from various quarters, with probably the most frequent criticism being that the Castle/Beckett relationship keeps getting bogged down in various angsty misunderstandings and 'roadblocks' designed to artificially stretch out the 'will they, won't they' angle (despite the fact that it's frequently made very clear that they ultimately will), in comparison to the more fresh and light-hearted approach taken in seasons one and two. It's fair to say that the ending of "Always" went some way towards mollifying many of these critics, however, and Word of God indicates that the fifth season will see a return to the more light-hearted approach taken by the first two seasons.
    • Season 8, mainly because Becket has gotten a case of Aesop Amnesia by leaving Castle to avenge the murder of her old AG partner. Even worse, there have been multiple characters who have made it quite clear that this is a very foolish decision to take, but their advice never takes root. This season's ratings are the lowest they have been for the show: Season 7 already had a significant dip in ratings, and it plummeted further in 8. Only a single episode of Season 7, the premiere, managed to break the 10 million viewer mark. And no episodes of Season 8 managed to hit even the 7 million mark until the final episode, by which point it was already too late as ABC had cancelled the show a few days beforehand.
  • Shipping Bed Death: Averted. The resolution of Castle and Beckett's Unresolved Sexual Tension only brought on a fresh new source of tension and humor, specifically how they keep their office romance a secret. Or fail miserably to, as it turns out.
  • Special Effect Failure: In "Hunt", the scene in which Castle talks on a payphone in Paris has him standing in front of a very obvious and fuzzy green screen. Turns a serious scene into Narm.
  • Strawman Has a Point: During the first half of Season 8 Kate is keeping Castle in the dark about her doing further investigations into her mother's murder, mainly to keep Castle safe. Castle is understandably angry over Kate feeling she can't trust him, and tells her he would have stayed out of her way is she wanted. While, Kate was wrong for lying to Castle (for a number of months), but long-time viewers will remember that Castle has generally disobeyed Kate's wishes a number of times in the past, or put his own life in danger recklessly, so it's not hard to see why Kate felt a need to lie to Castle in the first place.
  • Take That, Scrappy!: Alexis's entire rant about Pi in episode 13 of season 6 more or less sums up precisely why the viewers don't like this guy. A few episodes later, she reveals she broke up with him off-screen.
  • They Changed It, Now It Sucks:
    • In season 7, the revelation that Castle is friends with a mob boss meant he could no longer work at the precinct with Beckett, Espitio, and Ryan. So he got a PI license, working cases on his own without Beckett. Often the two were competing against each other to solve the case instead of together. Soon, however, status quo was restored.
    • The decision in season 8 to have Beckett separate from Castle so that she can pursue the shady CIA offical, who killed her old AG partner and Bracken to keep some dirty secret from coming to light., has naturally gone down like a cup of cold sick with much of the fans.
  • Too Soon: The episode "Still", which features Beckett being caught on top of a pressure-sensitive bomb, was pushed back one week following the Boston marathon bombings (and Boston ABC affiliate WCVB-TV elected not to air it even after it was pushed back). TNT failed to get a repeat of "47 Seconds" (another bomb plot) out of its Wednesday rotation and later apologized.
  • Unintentionally Unsympathetic: The use of Good Adultery, Bad Adultery in Food to Die For the killer's girlfriend left the victim because of his cheating ways yet still continued to sleep with him while basically using his foster brother to care for her and her baby by the victim (while leading him to believe it was his). This also applies to the victim while he came across as noble he tried to use money he got from his brother to run away with his wife. Is it any wonder when the guy found out he went crazy and killed him?
  • What an Idiot:
    • The killer in "That 70's Show". In a fit of rage, she killed a mafia boss which would have started a gang war if it wasn't covered up. Decades later, she hired someone to kill the only surviving witness, and since none of the evidence led to her, she essentially gave the cops a smoking gun.
    • The general fan reaction to Beckett leaving Castle in Season 8. She does it because a super powerful group that could kill everyone she holds dear is threatening her, and she knew Castle would never accept that she had to do this alone. Of course, the fact that she and Castle had already faced multiple super powerful enemies that could have killed everyone they hold dear together never crosses her mind, nor the fact that Castle was incredibly helpful in dealing with every crisis that came up (including getting his own daughter back from international terrorists). Not to mention that leaving him in the dark would only drive him to investigate and cause problems.
  • What Could Have Been: Season 7 "The Time of Our Lives" deals with what would have happened if Beckett wasn't the one that met Castle in "Flowers for Your Grave".
    • Bereft of a muse to write after killing Derrick Storm, Castle's next novel was heavily criticized, and he pretty much gave up, losing most of his money on the way and making him more withdrawn from his family.
    • Martha was forced to take her career more seriously to help with the money at home, with the result of it becoming more successful.
    • Alexis eventually left to live with her mother in Los Angeles (where she works in a NGO) and dyed her hair black, because she could not deal with how withdrawn her father became.
    • Beckett became the Captain (probably after Captain Montgomery retired), becoming even more Married to the Job than she was before they met and had a long string of boyfriends, but she never found her mother's killer.
    • The larger workload prevented Ryan from continuing his relationship with Jenny.
    • Esposito left Lanie pregnant, but his Commitment Issues led to them breaking up.
  • The Woobie:
    • Castle became this in the episode "Wrapped Up in Death" after supposedly being cursed by a Mayan Mummy. The fact that Beckett, Ryan, and Esposito kept playing pranks on him to make him believe in the curse only made it worse.
    • His face when he sees Beckett kiss Deming at the end of "Overkill" is absolutely heartwrenching.
    • Beckett at the end of "A Deadly Game" She begins to work up the courage to tell Castle how she feels about him, something which does not come easy for her, but just before she can his ex-wife Gina makes an appearance. The look on Beckett's face as they leave together speaks volumes.
    • For a while, Castle is this during the Season 3 opener "A Deadly Affair" because the entire precinct is giving him the cold shoulder for not returning sooner or calling at all during his absence. Sure, he deserves some of it, but you do feel a little bad for the guy after a while.
    • Cesar Calderon from "Anatomy of Murder" is an odd case. Yes, he's was a ruthless drug lord responsible for a lot of bad things... but he's also completely innocent in the murder and his horrified revelation of the killer is pretty darn heartbreaking. In fact, he was in love with the victim and it's implied he was going to marry her. The culprit? His own brother who killed her and tried to dispose of the body in the same way as in their drug lord days (ie no body at all so she basically just disappears). Even worse, there was no reason for her to be killed in the first place because the reason the brother thought was basically incorrect. Had the brother done the first thing Cesar says (talk to him and let them confront her about it), none of it would have happened at all.
    • Castle in "47 Seconds". He is about to tell Beckett for real that he loves her, but he gets interrupted by Esposito before he can do it, so he decides to do it later. However, when Beckett is interrogating a suspect, he goes to the adjoining room to hear the interrogation, and discovers that Beckett actually remembers everything that happened after being shot. He is, naturally, left broken at the fact that Beckett decided to deceive him, and the rest of the episode, when he is not helping with the case, he acts passive-aggressively towards Beckett.
      • Beckett might also count here as well, to some degree at least; despite keeping her secret, she was also planning on taking things to the next level and, unaware that Castle has found out her secret, is understandably bewildered and hurt by his sudden u-turn in attitude.

http://tvtropes.org/pmwiki/pmwiki.php/YMMV/Castle