* ActorLeavesCharacterDies: The producers were unable to get Creator/ShelleyMorrison to come out of retirement for the revival, so one episode had Rosario suffer a fatal heart attack while in the hospital.
* TheCharacterDiedWithHim: Will's boss Mr. Doucette (Creator/GregoryHines). The revival states that Grace's Mother Bobbi Adler (Creator/DebbieReynolds) passed away between seasons.
* FakeAmerican: For a while. Eric [=McCormack=] was born in Toronto, but became a US citizen in 1999.
* HideYourPregnancy: Debra Messing's pregnancy during the sixth season was ineffectually concealed by the standard bag of tricks: oversized clothing, wearing lots of black, belly-concealing props and so on. Messing ultimately had to skip five episodes that season on doctor's orders.
* HostilityOnTheSet: The on-set feud between Creator/MeganMullally (Karen) and Creator/DebraMessing (Grace) during the revival. Megan Mullally claims she has been "bullied at work" and their feud is the reason why Karen is strangely absent from two episodes of the final season.
* IAmNotSpock: When Creator/EricMcCormack hosted Saturday Night Live, during his opening monologue, he sang a song about how he is NOTHING like Will, mentioning his love for (among other things) Steve [=McQueen=] movies, beer, and Professional Wrestling.
* KeepCirculatingTheTapes: A number of the “supersized” episodes have only been released on DVD and streaming in their syndicated forms; the original, full-length versions have not been seen since their original airings.
* TheOtherDarrin:
** Creator/JohnSlattery originated the role of Sam, Will's older brother. Creator/StevenWeber eventually replaced him.
** Grace's older sister, Janet, was played by Creator/GeenaDavis during the original run. In the revival, Creator/MaryMcCormack took over the role.
** Grace's father, Martin, was first played by Creator/AlanArkin. When Arkin was unavailable for the revival, Robert Klein replaced him.
** Creator/ChrisPotter played Michael, Will's ex-boyfriend, back in season 2. Creator/CheyenneJackson assumed the role in the revival.
* QueerCharacterQueerActor: Creator/SeanHayes played Jack [=McFarland=] on ''Series/WillAndGrace'' but was not "officially" out during the show's initial run. When he "officially" came out in an ''Advocate'' article in the run-up to playing the gay title character in ''Sean Saves the World'' he took the position that he had "never been in". With the return of ''W&G'', Jack is at last played by an actor known to have a matching orientation.
* RealitySubtext: The b-plot of "The Scales of Justice" deals with Grace and Jack going to extreme lengths to lose weight. [[https://www.dailymail.co.uk/tvshowbiz/article-8605179/Debra-Messing-admits-way-skinny-Grace.html Debra Messing admitted to feeling the need to remain skinny during the show's original run.]]
* RealLifeRelative:
** In the episode "It's the Gay Pumpkin, Charlie Brown", co-creator David Kohan's daughter Olivia and assistant editor Todd Morris' daughter Bianca play trick-or-treaters.
** Creator/MeganMullally's real-life husband Creator/NickOfferman, now well-known as [[Series/ParksAndRecreation Ron Swanson]], played a plumber whom Karen had an affair with on Thanksgiving. He would later appear in the revival as Jackson Boudreaux (see YouLookFamiliar below).
** Posthumous example: Creator/BillieLourd has played Grace's niece, which makes her the granddaughter of the character played by Creator/DebbieReynolds, Lourd's actual grandmother (via Creator/CarrieFisher).
** Creator/JackBlack was dating Laura Kightlinger (one of the writers who also played the recurring character Nurse Sheila) when he appeared on the show in season six.
* ReferencedBy: ''WesternAnimation/Animaniacs2020'' referenced the show during their song about reboots.
* StuntCasting: Done an awful lot within a couple years -- it seemed like pretty much every high-profile gay-friendly celebrity in Hollywood was doing one-shots on the show. Music/{{Madonna}}, Cher, Music/JenniferLopez, etc.
* UnCancelled: Ten years after the show's original run ended in 2006, the cast reunited in 2016 for what was supposed to be a one-off short to encourage people to vote. It was surprisingly well-received, prompting NBC to soon bring the show back for ''two'' new seasons before adding a third to their order.
* WhatCouldHaveBeen:
** ''Creator/JohnBarrowman'' was one of the final candidates to play Will Truman, but they didn't think he was "gay enough."
** While attending the Sundance Film Festival, Creator/SeanHayes was asked to read for Will. Struggling for money at the time, he couldn't afford to change his flight to make the audition. Eric [=McCormack=] had been cast by the time he returned, so the producers asked if he'd like to read for Jack instead.
** Creator/MeganMullally originally read for Grace, which she claims did not go well. She was initially reluctant to play Karen, fearing the character was too similar to Maryanne Thorpe on ''Series/{{Cybill}}''. Ultimately, she just decided to make Karen "weirder," which helped her grasp the part.
** Creator/NicolletteSheridan was one of the finalists to play Grace. [[CastTheRunnerUp She later made a guest appearance]].
** There were discussions of a Jack and Karen spin-off, but after the ''Series/{{Friends}}'' spin-off ''Series/{{Joey}}'' got cancelled, the creators decided against the idea. Jack does some LeaningOnTheFourthWall in one episode, where he wonders aloud if maybe people somewhere are watching their lives unfold. Karen dismisses the idea because a ''Jack and Karen'' show would be "good for poops and giggles, but it would never last."
** Music/BarbraStreisand was long sought after to make a guest appearance but repeatedly declined offers. Both she and Creator/MerylStreep turned down the role of Karen's sister, Gin. Creator/BernadettePeters was ultimately cast.
** Megan Mullally spoke in 2009 of the idea for a Karen Walker musical on Broadway. She said it might feature Leslie Jordan as Karen's verbal sparring partner Beverly Leslie. Legal issues prevented the show from progressing very far.
** Rosario was initially planned to appear in the revival, but Shelley Morrison had retired and declined the offer to come back. [[spoiler:They killed Rosario off instead, while Morrison herself would pass away two years later.]]
** Creator/DaxShepard was initially chosen to play Jackson Boudreaux, but was fired after the first table read. Nick Offerman, Megan Mullally's husband, replaced him.
** [=McCoy=] Whitman was only supposed to appear once, but the producers liked Creator/MattBomer so much that they upgraded him into a recurring character.
* YouLookFamiliar:
** Amy Crofoot was a regular extra and occasional bit player. Her notable speaking parts include the school secretary in "I Never Promised You an Olive Garden," the NBC receptionist in "Acting Out," and the nursing student who sang "Hurts So Good" at Jack's graduation in "Speechless."
** Mary Pat Gleeson made two appearances as Sally, a kooky homeless woman, during the first run. In the revival, she appeared as Bridget, one of Karen's maids.
** Creator/NickOfferman first appeared as the plumber Karen contemplated an affair with during the series' original run. In the revival, he returned as Jackson Boudreaux, a bisexual chef interested in both Will and Grace.
** Kyle Bornheimer played a waiter in season 8. In season 9, he played Secret Service agent Lenny, whom Jack is sweet on.
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