Replacement Love Interest

"How I missed her, how I missed her How I missed my Clementine. But I kissed her little sister I forgot my Clementine."

- My Darling Clementine

In an action movie, the hero's True Love has died in the hands of the villain, with just enough time for a few parting words that will give him the strength to defeat the Big Bad. In a comedy, the love interest simply dumped the protagonist and married the Romantic False Lead. In a Trapped in Another World adventure, it's time for the hero to return to Our World, and the love interest tearfully says she can't leave her world and go home with him. Any which way, the protagonist is left heartbroken and crestfallen because he didn't get her.

But... wait a minute! Isn't that girl a close Captain Ersatz of the one he just lost? (She's often played by the same actress with a new haircut.) The attraction is as instantaneous as it is mutual. Time to roll the credits!

Note that this trope is specifically for situations where the character is an obvious replacement, but not the exact same person in a new body. That's Doppelganger Replacement Love Interest. Also see Suspiciously Similar Substitute, where the issue is the actor leaving the show. Often used as a form of Cleaning Up Romantic Loose Ends. Compare to Replacement Goldfish for the Non-Romantic variant. See also You Remind Me of X.

Anime & Manga
"Hayate's thoughts: Will it happen again? Will another day come where I can tell someone I truly love them once more? "
 * Played with in a chapter of Ouran High School Host Club, with a new character being referred to by the Club Members (except Haruhi and Tamaki) as the "Ideal Haruhi" because in addition to bearing an uncanny resemblance to Haruhi, she lined up almost perfectly with Tamaki's daydreamed version of her.
 * Fushigi Yuugi.
 * Hayate the Combat Butler: While there's no mutual romance thus far, a lot of the Ship Tease during the latter half of the Athena arc pointed out (explicitly and implicitly) just how many similarities Nagi shared with Hayate's first love, Athena. One bit of cover art even featured the both of them put side by side, and they're both referred to in-story as golden-haired girls who saved him from despair by taking him on as a Battle Butler. Said arc culminated in absolutely brutal Ship Tease that threw shippers in a frenzy.

Comic Books

 * In their pre-Avengers stories, this trope was in effect for Hank Pym (Ant-Man/Giant Man) and Janet van Dyne (The Wasp). Though she had a massive crush on him, she was both underaged at the time, and bore a disturbing (to him) resemblance to his recently-murdered wife. They eventually ended up hooking up anyway, and the resemblance issue was never mentioned again until after their divorce.
 * In X-Men, Scott falls for Madelyn shortly after Jean's death. They look so similar that he actually believes she's Jean's reincarnation, though he eventually accepts them as different people. Played With when Jean comes back from the dead and Scott abandons Madelyn, who is his wife by this point. And then it's revealed that Madelyn is actually a clone.

Film

 * Happened in The World Is Not Enough with Denise Richards as Christmas Jones. She gets introduced a bit before the first Bond girl is revealed to have pulled a Face Heel Turn just so Bond has someone to kiss before the end credits.
 * Happens rather more often than is healthy for Bond, actually.
 * Perhaps the most egregious example is the replacement of Aki with Kissy (whose name isn't even mentioned in the film) in You Only Live Twice.
 * Then again, one might argue that these women are not as much love interests as one night stand material to James Bond, which makes it less mind boggling and explains why they're always gone in the next film.
 * Mirror Mask: Helena hooks up with Valentine's human counterpart at the end. Although Helena and Valentine himself didn't flirt, not counting her telling her mother that He Is Not My Boyfriend.
 * The movie The Forbidden Kingdom.
 * Also happened in Chaplin.
 * Implied to happen in The 500 Days Of Summer. After the main character is unable to make a romantic relationship work with a woman named Summer, he happens across an interesting woman named Autumn and starts talking to her.
 * Also happens in Night at the Museum 2, where Larry sadly leaves Amelia Earhart behind at the Smithsonian (sans magical artifact, so she'll never come to life again) and promptly meets an identical modern girl in New York.
 * Happens in the 2000 remake of Bedazzled, starring Brendan Fraser and Elizabeth Hurley. In the end Elliot (Frasier) wishes his beloved just to be happy, and is gently dumped by her when she mentions she already has a boyfriend. Going home, he meets his new neighbor, which happens to be the same actress with different hair. He even hangs a lampshade on this by asking her if she has a sister.
 * In the animated movie Starchaser: The Legend of Orin the original love interest  but no worries, in his adventures he'll soon find a princess on another planet to fall instantly in love with, voiced by the same actress.

Literature

 * In the novel Heir Apparent by Vivian Vande Velde, the protagonist spends most of the book trapped in a malfunctioning virtual reality game in a high fantasy medieval setting. At the end of the book, she finally beats the game and wakes up - cradled in the arms of a man who looks exactly like the game's Troubled but Cute love interest. Turns out he is the game's designer, and he modeled the virtual character on himself...
 * In Germline the main character fall in love with a Genetic in the beginning who killers herself, but then later he meets a clone of her that he falls in love with.
 * Word of God in Harry Potter is that Angelina Johnson, who was Fred Weasley's date at the Yule Ball, married George Weasley.
 * Near the end of Steven King's Dark Tower, Susannah, travels through one of Patrick's doors to an alternate version of New York where she meets an Eddie and Jake Toren, a different Eddie and Jake from the ones she knew, from a little further out on the beam from the keystone world, but close enough for her.
 * This is essentially the premise of The Vampire Diaries, when Stefan sees a girl who looks exactly like the vampire who turned him and his brother, presumed dead for 150 years, and decides he has to get to know her. Since this happens at the start of the series, things don't go so smoothly as in most examples.
 * In The Children of Hurin, a few months after Turin's blonde sort-of Love Interest Finduilas dies he finds a naked, blonde amnesiac girl lying unconcious on her grave. He sees this as a sign, and they fall in love..

Live Action TV
"Logan: So you're saying it's just a coincidence that Gretchen looks exactly like Zoey? Chase: I don't even see a resemblance. Michael: Everybody thinks they look alike! Logan: And that's the only reason you're hanging out with her! She's your little Zoey replacement, and that's a little bit sick."
 * The fourth series finale of Doctor Who, with Rose earning the half-human Handy (Doctor 10.5) as a consolation prize.
 * When the Mighty Morphin Power Rangers came back from time travel, Adam was forced to say goodbye to his love interest Marissa. At the end of the episode, he bumps into a girl played by the same actress and is implied to be her descendant. Two odd things about this example: they were coming back from a California that was colonized by England; Marissa was a highly uncommon name in the 1700s. Though when the English are in charge of California, all bets are off.
 * A more mundane version happens later in Power Rangers Zeo: Tommy gets dumped by former Pink Ranger Kimberly, but soon becomes involved with Katherine, the new Pink Ranger and Kim's Suspiciously Similar Substitute.
 * They weren't that similar. Kim was a brunette american gymnast, Kat was a blonde australian diver.
 * In the pilot of Harsh Realm, Hobbes meets the virtual double of his fiance Sophie.
 * In the pilot of Time Trax, no wonder he falls in love with her—she's his dead love interest's Identical Great-great-great-etc. ... grandmother.
 * Probably part of the reason that Riley Finn is so disliked by the fandom is because he practically had the words 'Buffy's new love interest!' flashing in bold neon lettering over his head in his first appearance.
 * I'll see your Riley Finn and raise you Kennedy.
 * After Maid Marian is killed off in the BBC's Robin Hood, a village girl called Kate is introduced as Robin's new love interest. As you might have guessed, the audience's reaction to replacing the legendary Marian with a random villager as Robin Hood's girlfriend went down like a cup of cold sick. However, sometimes, a replacement character manages to bring something of their own to the table, become more than just the person who's in your face instead of the character who is "supposed" to be there, and become quite beloved on their own. Kate is most definitely not one of these cases, being a Scrappy, a Damsel Scrappy, and being talked up by everyone while showing not a single positive trait we're (repeatedly) told she has, or a single positive trait period.
 * Heartbeat practically lived on this, with almost every village constable getting one. When PC Nick Rowan's wife Kate died, he was quickly introduced to Jo Weston, who became his second wife. When PC Mike Bradley's wife Jackie left the show, he was quickly linked to Tricia Summerbee (although the two characters did cross over for a bit). When PC Rob Walker's wife Helen was killed, he soon met Carol Cassidy, who stayed on the show long enough for Walker's successor PC Joe Mason to be her Replacement Love Interest.
 * Chase in Zoey 101 attempts to do this when Zoey leaves for England. But while the replacement looks like Zoey, she's not very pleasant in the personality department. And the fact that Chase is trying to replace Zoey with someone else kind of freaks out his friends.


 * Niles' second wife Mel Karnofski in Frasier — a fussy, domineering, hysterically-inclined, nervous woman whose behavior (and the characters' reactions to it) made it clear that she was a saner, less abrasive version of Maris, Niles's Jerkass of a first wife, despite Maris being The Ghost. This is actually something that often occurs in real life with people who have recently gotten out of unhealthy relationships.
 * This is what fans assumed John Doggett would be for Scully on The X-Files while Mulder was abducted. He wasn't, and the writers/creator were very explicit in saying that Doggett was not a love interest for Scully or a replacement for Mulder. It still didn't stop the fans from hating his guts.
 * Ironically, they also wound up with a faction of Scully/Doggett shippers who were annoyed he wasn't a Replacement Love Interest. By then the fanbase was near-catastrophically broken anyway.
 * Sully on Bones.

Theater

 * In the musical One Touch Of Venus, Rodney Hatch is promised by Venus (his divine Magical Girlfriend) he'll never be lonely for the rest of his life, but being the 1940s housewife he sees her as doesn't appeal to her. So she goes back to her ancient homeland without saying goodbye. He's wondering about her promise when he suddenly meets a Country Mouse with a familiar face (since she's played by the same actress) who's willing to settle in the suburbs with him.

Video Games

 * Super Mario Bros.: In the Donkey Kong arcade game, Pauline was Mario's love interest and girlfriend. But in Super Mario Bros. Nintendo introduced Mario with a new love interest: Princess Peach. They don't look much alike, but they're similar enough (particularly in their early 8-bit graphics forms) that many people have assumed that Pauline is Peach.
 * Lampshaded and then deconstructed in Silent Hill 2. When James meets Maria, he remarks on how similar she looks to his deceased wife, Mary.
 * Haseo has this happen in .hack//GU when he meets Atoli, who is a literal Palette Swap of his old love interest Shino (perfectly Justified: this all happens in an MMO). However, Atoli is decidedly not Shino in terms of personality, something that disturbs Haseo greatly at first, though he later accepts her as her own person.

Web Comics

 * Inverted in Kevin and Kell: George Fennec falls in love with Kevin's sister Danielle, who dies helping the main cast defeat a rabbit terrorist group. Shortly afterward, her double from the human world gets trapped on 'Furth', and due to the nature of the portal between worlds, becomes Danielle in appearance.
 * Sluggy Freelance in the That Which Redeems story, with the twist that each of them were already in love with the version from their own world.

Western Animation

 * Rudy Mookich from Pinky, Elmyra and the Brain is a Nelson Muntz Expy who replaced Montana Max as Elmyra Duff's love interest. Danny Cooksey (Monty's voice actor) must have refused to do the spin-off.
 * Cooksey was probably never asked in the first place. That whole show seemed determined to prove that Tiny Toon Adventures never existed.