You Remind Me of X doesn't count. See also Easy Impersonation, when it's a villain being mistaken for a hero.
Examples:Anime & Manga
- In Inuyasha, everyone initially compares Kagome to Kikyo. They may technically have the "same" face (as it turns out they have the same soul), but when the series suffers from Only Six Faces and Kikyo and Kagome purposefully differ in hair style, habitual facial expressions, skin tone, and age, they don't look alike at all - at least, not any more alike than any other two random characters you could pick out. The anime has it worse, so that it's almost an Adaptation-Induced Plot Hole there.
- In Yu-Gi-Oh!, no-one ever seems to see a difference between short, moe, Tareme-eyed, soft-voiced Yugi and his not-quite-so-short, bishonen, Tsurime-eyed, deep-voiced alter ego. Some fans have tried to explain the (apparently not so) obvious changes as audio-visual cues to the audience that do not actually exist in-universe. Since every once in a blue moon somebody will mention one of the changes in passing, this explanation has not been widely accepted. Maybe the others just can't stop staring at the hair.
- The manga averts this, actually. They all notice the switch between Yugi and his alter ego or at least they notice that he changed.
- Something similar happens Yu-Gi-Oh! ARC-V. Yuzu comes across with Yuto who looks exactly like Yuya does... except not really. They have similar faces, but their hair, voices, clothes, and mannerisms are completely different. Despite this, Yuzu stays uncertain for a long time that they're really not the same person. Several other characters comment on how he looks exactly like the splitting image of Yuya. There's also Yugo, who looks even more different from Yuya than Yuto does, but once again the show insists that they look exactly alike. Then we met Yuri who looks even more different than Yuya but everyone again says the same thing. And then there are Yuzu's looklikes Ruri, Serena and Rin, but the resemblence between them is stronger than Yuya and his lookalikes.
- In Card Captor Sakura Sonomi comments on how much Sakura looks like her mother, to the point of being surprised at the resemblance before she even knew who Sakura was. Yet there is no noticeable resemblance between them (Touya actually looks much more like their mother than Sakura does).
- This is mostly a side effect of the art style; CLAMP draws adults with long faces, but children with shorter, rounder ones. The result of this is that Sakura's adult brother looks far more like their mother than she does, making it impossible for readers to spot the resemblance. For instance, look at an older alternate version of Sakura in Tsubasa Reservoir Chronicle: the resemblance between her and her mother is more noticeable.
- In Digimon Frontier, people marvel at the near-identical Koji and Koichi, who like Kagome and Kikyo, don't particularly resemble beyond the things everyone has in common due to having the same art style (meaning they resemble about as much as any one person resembles anyone else with the same hair color.) Maybe you could handwave the totally different skintones as one spending more time in the sun than the other. (It leads up to their being revealed as each other's long-lost twin. Fraternal twins do exist, but again, we get "they look exactly alike!" Once an Episode.)
- An interesting case happens in JoJo's Bizarre Adventure because of the artist's style changes. Part III protagonist Jotaro Kujo is supposed to look identical to his grandfather Joseph Joestar in his 30s, to a point Joseph's mistress Tomoko Higashikata mistakes him for her lover. Jotaro's appearances in Part III, IV, and VI are all during the Art Evolution periods, meaning that Jotaro never looks like Joseph in the slightest to the readers, unless you count Araki's recent redesigns, which suffer from an extreme case of Only Six Faces.
- In-Universe in the Harley Quinn comics. The third issue has a man who says he can never hold down a job because he looks just like...The Joker (Harley had guessed Al Gore with a bad haircut). He doesn't and is clearly delusional, eventually leading to his own death out of sheer idiocy.
- Happens in Kamen Rider: The First, where the woman only spots one of the two Hopper operatives in night time, making it harder to distinguish their Palette Swap. On top of that, she's seen Hopper no. 1 without the helmet once, but because of aforesaid problems with color perception, she doesn't know that it him who saves her later since he keeps the helmet on this time, AND she comes across Hopper no. 2 in the daytime and thinks that's the one who saved her. That would make sense in the show, where for the longest time, only small details kept them from being 100% identical. But this being the big-budget remake, the producers knowingly pimped out the suits with heavy detailing just to make sure you weren't counting arm-stripes to tell them apart.
- In the very goofy 1991 movie Mystery Date, everyone confuses Ethan Hawke with Brian McNamara (playing his older brother), despite the fact that the two bear next to no resemblance to each other. Seriously. They even claim to give Ethan Hawke the same haircut, but he still has that bowlcut style haircut he had in every movie he made in the early 90s. It's ridiculous.
- In Gattaca, the fact that Vincent is able to disguise himself as Jerome using his DNA samples is believable, but, looks wise, they aren't that similar. Jude Law and Ethan Hawke just don't look alike, at least not enough to confuse one for the other. This is handwaved in the movie as people (especially cops) being so confident in their genetic analysis material that "who looks at the face, nowadays?". The only person to notice is the Love Interest who's surprised when she meets the real Jerome.
- A big plot point in The Black Dahlia is that Madeleine Linscott and the murdered Elizabeth Shortt looked alike. Kay is even able to spot the resemblance from several feet away on the lawn. Actresses Hilary Swank and Mia Kirschner look nothing alike.
- In Repo! The Genetic Opera, Mag comments that Shilo has her "mother's eyes, her hair" - the eyes are debatable, but the hair looks nothing alike, Marni's hair being slightly lighter and curly. Especially noticeable since Shilo's "hair" is a wig supplied by her father.
- The Great Muppet Caper had a running gag in which Fozzie and Kermit were supposed to be twins and they can only be told apart when Fozzie has his hat on.
Fozzie: You're lucky. You have fur.Kermit: No, Fozzie, you're the one with the fur. Turn on your light and see for yourself.
- Gets even funnier when they get each other confused while simultaneously acknowledging their obvious physical differences:
- An episode of NewsRadio had this as part of the plot. Matthew's 'twin brother', played by pre-Daily Show Jon Stewart, came to visit. He looked nothing like him, but they both kept playing 'look alike' games. Eventually Matthew's brother says that it was a stupid idea of his parents in order to misdirect Matthew from thinking he was adopted. The rest of the cast is shocked, as this is incredibly stupid, even for Matthew. It turns out that the deception was the other way around. Matthew was the biological son, and he was simply playing stupid in order for his brother to not think he was adopted.
- In Sykes Eric and Hattie insisted they were identical, despite not only being the opposite sex but also being completely different body types (Eric being taller, thin, and rakish and Hattie being shorter, heavier set and baby faced).
- In an episode of Xena: Warrior Princess, Gabrielle and Aphrodite have to infiltrate a twins bar run by the Gemini twins, despite not remotely looking alike (Aphrodite is a good deal taller than Gabrielle, for starters).
- Metastises horribly with an Obvious Stunt Double in the Doctor Who story "The Chase", in which the Doctor's Evil Knockoff is played by William Hartnell's stunt double even in scenes when only one character had to be shown. The evil Doctor is said to be indistinguishable from the other in every way, which is reaching. The two actors do look very similar, but still readily distinguishable.
- There's a Professional Wrestling duo named the Dudley Boys/Team 3-D where one of the "twins" is white and the other's black. The official explanation is that they are "Brothers From Another Mother". They even managed to once pull the switch places when the ref isn't looking trick.
- Swan Lake: The daughter of the Bad Guy goes to a dance disguised as the white swan. We know it's her because she's dressed in black.
- Les MisÚrables: Champmathieu is supposed to look exactly like Jean Valjean, but in practice the actors are seldom identical.
- Comedyof Errors: Two long-lost identical twins end up in the same town. In some productions, the twins are played by different actors, and even, depending on the producer, different races and/or genders.
- In Kingdom Hearts II, the members of Organization XIII keep calling Sora "Roxas". This is... confusing, since to some degree they seem to actually believe he is Roxas, but they're also messing with his head, and it's hard to tell which is happening.
- With later revelations about the nature of Roxas and nobodies, the Organization had reason to believe that Roxas could become the dominant persona. However, as Roxas had personal reasons to hate the Organization, getting him to take charge would have been bad for them.
- In Sonic Adventure 2, Sonic is constantly being mistaken for Shadow, another hedgehog. Shadow has upturned spikes, is black and red (rather than blue), and uses hoverskates. Their only similarity is that they're both fast hedgehogs. This is especially bad since, at the speeds they normally move, their superficial similarities would result in being seen as "A blueish blur" and "a red blur." Additionally, Sonic's self-proclaimed girlfriend got them mixed up, not even when they were moving fast.
- Tokimeki Memorial 4: It's certainly true that Rui Nanakawa looks like Tadashi, but she's still a girl. Even when in his clothes, Rui is a head shorter, has a higher pitched voice, lighter skin, and certainly isn't lacking in the bust department. No one seems to notice these differences except the Protagonist.
- Phoenix Wright and Furio Tigre in Phoenix Wright: Ace Attorney. Played for laughs since the only thing Furio shares with Phoenix is a hair style. They differ in build, temperament, facial features, and skin tone yet Tigre successfully managed to impersonate Phoenix in court using a fake badge made of cardboard with no one thinking it was anything other than slightly odd.
- Played with in Welcome to Night Vale. Cecil and Kevin are mentioned to be completely identical, aside from the latter's Black Eyes of Evil. This carries over to the live version, where it can be clearly seen that Cecil Baldwin and Kevin Free look practically nothing◊ alike◊. Word of God says that only the descriptions in the podcast are canon, which are so far irrelevant to anything besides clothing.
- Family Guy: Brian is in a Spot the Imposter situation between Regular Stewie and EvilerThanUsual Clone Stewie. We can tell which is which because they have reversed color schemes on their clothes: Regular!Stewie has red overalls with a yellow shirt and ETUC!Stewie has yellow overalls with a red shirt.
- At least until the inevitable fight where they both get the overalls ripped off, leaving two Stewies in diapers. (quickly lampshaded)
- Exaggerated Trope in "German Guy" when Chris gets in a Spot the Imposter situation with Peter and an elderly Nazi. Peter remarks that they don't look anything alike, but it doesn't help.
- Played for Laughs in Back at the Barnyard. The other dog who was impersonating Duke looked nothing like him.