History Main / TheMistress

* ''Series/InterviewWithTheVampire2022'': Antoinette Brown is this for Lestat de Lioncourt, who is in a [[MetaphoricalMarriage committed relationship]] with Louis de Pointe du Lac. Whenever Lestat feels that Louis isn't paying enough attention to him sexually, he "entertains" and "amuses" himself with Antoinette instead.

* In ''LightNovel/FateZero'' Kiritsugu and Maiya have known each other for a long time and have been sleeping together for some time, even after his marriage to Irisviel and despite the fact that Kiritsugu actually loves his wife.
* Akeno takes the place of Issei's Mistress in ''LightNovel/HighSchoolDXD''. In a twist, TopWife Rias is not only aware of this, but openly condones it, since Akeno is her best friend and Rias knows Akeno has a kink for being the other woman. Even when the rest of Issei's harem eventually marry him and take his name, Akeno never does - it's hard to cheat with your own husband!

** [[UsefulNotes/TheHouseOfWindsor Edward VII]] famously had a number of mistresses and affairs, particularly during his fifty-plus-year tenure as Prince of Wales. His most famous were Daisy Grenville, the Countess of Warwick (more commonly known as "Babbling Brooke" because her husband had the subsidiary title "Lord Brooke" and because, well, she [[CannotKeepASecret babbled]]); the actress Lillie Langtry;[[note]][[BeamMeUpScotty Supposedly]], while the relationship between Langtry and the Prince was fraying, he frustratedly asked her, "Why should I spend any more money on you? I've spend enough on you to build a battleship!" Langtry supposedly replied, "And you've spent enough ''in'' me to float it."[[/note]] and finally Alice Keppel, with whom he lived during his reign (1901-1910). Edward's wife, Alexandra of Denmark, was generally OK with this--she seems to mostly have been amused by it, especially given that both he and his mistresses were generally overweight and therefore cut rather comic figures together. His dalliances did sometimes get him into trouble; he was famously compelled to testify in a divorce case (the first heir apparent in ages, if not ever, compelled to take the stand) when he was caught carrying on with an MP's wife while the MP was attending sittings of Parliament.

* ''WebVideo/SabatonHistory'': {{Parodied}} in the producer segment for [[https://www.youtube.com/watch?v=PX9y7z1qndQ "The Last Battle"]] when Joakim facetiously refers to "Jenny" from the song as "my secret lover". (The line actually refers to ''Besotten Jenny'', the M4 Sherman tank that [[https://en.wikipedia.org/wiki/Battle_of_Castle_Itter Captain Lee brought with him to Castle Itter]].)
-->'''Indy:''' Does your ladyfriend know about her?\\
'''Joakim:''' I hope not! ''(cut to TV color bar screen)''

->''These are not the short-term flings, the one-night stands, or the casual extramarital friends with benefits. They are long-term lovers who have spent years, sometimes decades, single and involved with married men. [...] This seems to be more typically a female variety of suffering, and it’s no accident that the epithets applied to them do not have masculine equivalents. [...] I have met plenty of men who were the lovers of married women (or married men, for that matter). But I have yet to meet a man who was single and gave his love to another man’s wife for thirty years, hoping that she would leave and come and make a family with him.''

* In ''The Literature/LastHeraldMageTrilogy'', King Randale's [[MindlinkMates beloved]] Herald Shavri is officially this, mainly because the option of a State Marriage had to be left open. Shavri even talked Vanyel into siring a child upon her in large part to hide the fact that a wasting disease had rendered the king sterile (little did she know that said "byblow" would marry into the [[SecretLegacy collateral line that eventually got the throne]]).

Compare TheUnfairSex, OopsIForgotIWasMarried (if the mistress does not know about the other's family), DarkMistress (who is not an evil version of this, despite the name). Many a TrophyWife starts out this way, although it is by no means guaranteed that she'll eventually become his wife...or, for that matter, that every (usually second or third) marriage between [[MayDecemberRomance an older (and usually rich) man and a younger woman]] started out this way. Mistresses in a setting with Islamic and/or Asian influence often live in a RoyalHarem. When the mistress has kids, and the man helps her raise them behind his wife's back, that's SecretOtherFamily. See also GoodAdulteryBadAdultery. And if you can think of a perfectly equivalent, accurate term with the exact same connotations for the [[DistaffCounterpart Spear Counterpart]], please let us know -- society has yet to come up with one.

* ''Series/InterviewWithTheVampire2022'': Antoinette Brown is this for Lestat de Lioncourt, who is in a committed relationship with Louis de Pointe du Lac. Whenever Lestat feels that Louis isn't paying enough attention to him sexually, he "entertains" and "amuses" himself with Antoinette instead.

* ''Film/{{The Other Woman|2009}}'': Emilia plays the eponymous role. She has an affair with Jack, who's married. After becoming pregant with their baby, Jack divorces his wife and [[RemarriedToTheMistress marries Emilia]].

* ''LightNovel/AscendanceOfABookworm'': Taking mistresses is apparently a common practice among high-ranking men, to the point that young girls are sometimes promised as future mistresses as some sort of loose equivalent to an engagement. Noblemen, even the most low-ranking ones, are absolutely not supposed to properly marry outside of nobility, so the only NobilityMarriesMoney arrangement that is mentioned in the story has the "money" side slated to become a mistress. The male head of the temple doesn't have a wife, but plenty of mistresses. The children of mistresses are considered illegitimate children despite this, though having a noble father can let them get a few perks of nobility such as going to the setting's WizardingSchool.

** In a rare male example, Loras Tyrell fulfills this role when his lover Renly Baratheon marries Loras' sister Margaery. Verges on an OpenSecret, if the amount of sarcastic references to the relationship is any indication. At one point the exclusively homosexual Renly is trying to make excuses for not consummating the marriage, to which Margaery suggests in all seriousness that they bring Loras in to "get him started". Renly thinks this is an insult, but she actually fully accepts that the marriage [[TheBeard is a political sham]] while Loras is his real lover; she just thinks [[HeirClubForMen they need to have an heir to cement the alliance]].

* This is used for DeliberateValuesDissonance in ''Fanfic/{{Kindred}}''. Aurora casually mentions that her father has eight mistresses (with one of them supposedly giving Aurora a half-sibling) and Mulan mentions that her father has one as well. Jasmine's father had a harem until he killed them all because one of them wasn't faithful while the emperor of China has several hundred concubines.
* ''WebVideo/AnastasiaQuasimodoWeHitAWall'': The story starts wifh Lady Tremaine finding out about her husband's young mistress, Esmeralda. In the end, she has her killed, though this leads her husband to [[DrivenToSuicide kill himself]] a few days later.

*** Prince Edward, Duke of Kent and Strathearn, was a famous serial monogamist, living long-term first with two different Swiss women in succession, and then for 27 years with Thérèse de Montgenêt de Saint-Laurent, the wife of a French nobleman and cavalry officer whom he had met in Geneva.[[note]]She had no children with him, despite what some Canadian families will tell you.[[/note]] He broke it off with Mme. de Saint-Laurent after the death of his brother George's only legitimate child Charlotte created a looming SuccessionCrisis, marrying a German princess (Victoria of Saxe-Coburg-Saalfeld) and producing the desired heir (the aforementioned Victoria).

* ''Series/{{Bridgerton}}'': In season 1, the bachelor Anthony Bridgerton has been in a [[SecretRelationship clandestine relationship]] with his mistress, Siena, for quite a long time. Despite it's an OpenSecret, yet Anthony's family never know about their affair. After Anthony seems to finally be ready to go public with her, she suddenly changes her mind and eventually breaks off their relationship.

** And of course, [[UsefulNotes/TheBritishRoyalFamily Charles III]] famously had an affair with Camilla Parker-Bowles for many years throughout their respective first marriages, off and on from ''1971'', before finally marrying her in 2005, by which time the sting of his ex-wife Diana's death wasn't so fresh. Interestingly, Camilla's great-grandmother (mother of her maternal grandmother Sonia Cubitt) was none other than Alice Keppel. Even more interestingly, Alice Keppel's husband, Camilla's great-grandfather George Keppel, was himself a descendant of...Charles Lennox, 1st Duke of Richmond, a.k.a. one of Charles II's aforementioned illegitimate sons. (The upshot? Even if Prince Charles had been allowed to marry Camilla as he had wanted in the late 1970s, his heir would still be descended from one of Charles II's bastards.)

** And of course, [[UsefulNotes/TheBritishRoyalFamily Prince Charles]] famously had an affair with Camilla Parker-Bowles for many years throughout their respective first marriages, off and on from ''1971'', before finally marrying her in 2005, by which time the sting of his ex-wife Diana's death wasn't so fresh. Interestingly, Camilla's great-grandmother (mother of her maternal grandmother Sonia Cubitt) was none other than Alice Keppel. Even more interestingly, Alice Keppel's husband, Camilla's great-grandfather George Keppel, was himself a descendant of...Charles Lennox, 1st Duke of Richmond, a.k.a. one of Charles II's aforementioned illegitimate sons. (The upshot? Even if Prince Charles had been allowed to marry Camilla as he had wanted in the late 1970s, his heir would still be descended from one of Charles II's bastards.)

* ''Series/{{Bridgerton}}'': In season 1, the bachelor Anthony Bridgerton has been in a clandestine relationship with his mistress, Siena, for quite a long time. Despite it's an OpenSecret, yet Anthony's family never know about their affair. After Anthony seems to finally be ready to go public with her, she suddenly changes her mind and eventually breaks off their relationship.

* Set in (last years) Victorian England, Count Roland of Under The Rose manga has two mistresses. One is glamorous, pretty, dughter of [[ImpoverishedPatrician declined Marquis]] Grace King and [[TheDitz clumsy]], [[GirlNextDoor plain jane]] who was [[TeacherStudentRomance his former intern]] Margareth Stanley. It says a lot when each of the mistresses has more active role in children, sans William who is his mother's (legitimate wife) favorite. Yes, it is Seinen featuring Disfunctional Family.

* ''Series/{{Bridgerton}}'': In season 1, Siena Rosso has been Anthony Bridgerton's mistress. Despite it's an OpenSecret, yet Anthony's family never know about their affair. Despite Anthony seems to finally be ready to go public with her, she suddenly changes her mind and eventually breaks off their relationship.

* ''Series/{{Bridgerton}}'': In season 1, Siena Rosso has been Anthony Bridgerton's mistress. Despite it's an OpenSecret, yet Anthony's family never know about their affair. Despite Anthony seems to finally be ready to go public with her, she suddenly changes her mind and breaks off their relationship.

** ''''VideoGame/PrincessMaker2'':

* ''Film/ThePrincess'': Moira is Julius' long-term lover, though he's going to marry the princess. She seems fine with that, and he likely can't marry her as she's a commoner.