This is when two characters have been friends for a long time, and share a closeness like that of a long-term married couple. Occasionally, there are individuals who assume the duo are married or dating, or wonder, "Why aren't you guys dating?" or try to set them up as a couple. However, the duo is perfectly happy just being friends and the lack of sexual attraction is mutual. The reasons behind this vary. Sometimes they're truly in love with someone else. Sometimes it's just how they feel. Sometimes they even tried dating once a long time ago and realised that they just don't think about each other like that. Whatever the case, the final result is entirely platonic on both sides.
Simply being friends doesn't make a pair an example, nor does just being True Companions. Can lead to shipping of preferred characters by those who disregard the difference between Eros and Philia. To the disappointment of shippers, though, there's a good reason they're called Platonic Life Partners. In terms of The Four Loves, this is Phileo with overtones of Storge.
In most cases, this is a sub-trope of Like Brother and Sister. The difference is that for Platonic Life Partners, their relationship with each other is the most important relationship, with even romantic relationships coming in second. There are also variations on this, including where one character is gay or bisexual, or when the sexual orientations of the characters involved are not clear such that Unresolved Sexual Tension could be theoretically probable. The same-sex equivalent is Heterosexual Life-Partners. In real life, being Like Brother and Sister often entails a more physical relationship, whereas this trope involves more emotional relationships.
Before you add an example to this page, make sure it really fits the trope. Harry Potter and Hermione Granger are a good example of two characters who don't belong here. Although they are close friends, they are both closer to Ron than they are to each other.note It is made especially clear in Goblet of Fire that Ron is Harry's best friend over Hermione. And Hermione is presumably closer to Ron than Harry, at least by the end of the series. They're Like Brother and Sister.
Subtrope of The Not-Love Interest. Compare Better as Friends. Contrast Just Friends for when this does actually blossom into romance. Not to be confused with Unlucky Childhood Friend in which one side does have feelings for the other.
Setsuna and Marina from Gundam 00 based on the movie. Both consider each other their most important person? Check. An almost spiritual connection when apart? Check. Setsuna comparing Marina to a flower blooming on a parched ground, and wanting to be someone who will die just to protect that one single flower... Marina comparing Setsuna to the sky, and how she vows to be his 'measure of eternity'. Both of them vowing to meet again when the time is right, staying single and unmarried for 50 years until Setsuna finally returned to her? Check. Not a single romantic feeling involved?CHECK.
Toyed with in the manga adaptation of the movie. While Marina and Setsuna do get married there, the mangaka explicitly stated that their marriage is purely symbolic to their mutual understanding of each other. Also, since 50 years have passed she's an old woman anyway while he fused with the ELS. So probably not the kind of mushy romantic feelings the fans would expect involved either here...
Maybe they're both just asexual. Due to his Dark and Troubled Past as a child soldier, at least Setsuna definite is, anyway.
Soul and Maka from Soul Eater are sharing this exact relationship. They're definitely each other's primary relationship - the series is based on one character that is a weapon (or a person who turns into a weapon or... it's weird and ambiguous) bonded with one character that is a wielder, and thus are constant companions and the most important people to each other. Except that there is a good deal of Ship Tease around the two.
A majority of the relationships between the Meisters and their respective weapons are this in truth. And according to Wordof God it's going to remain this way since he doesn't plan on developing the relationships into anything romantic.
Asuna and Negi in Mahou Sensei Negima!, although Negi's natural charm makes this hard at times. It later turns out that they're related- Negi's mother Arika is a relative of Asuna's, likely her step-sister or descendant, though the exact nature of the relation has yet to be revealed. For maximum awkward value, at about the same time that was confirmed, it was revealed Asuna's doppelganger Shiori/Luna at least seems to believe that Asuna loves him... after having taken up and absorbed Asuna's memories to replace her while she's held hostage by Fate Averruncus. Definitely settled almost at the end, where Asuna does kiss Negi on the lips... but as a good-bye before she goes into a century-long sleep for plot reasons, and then she tells him to give good thought to which girl he will willingly kiss later.
This can easily be said of Tara, Shuri's great-grandmother, and Genshou, Sarasa's great-grandfather, in Basara's side stories.
Aside from Nitori briefly believing she was in love with Takatsuki, Nitori and Takatsuki from Wandering Son fit.
Averted in the end. In the later chapters Takatsuki reveals she has a crush on Nitori, and their relationship has gone distant since high school began
Shizuo and Celty from Durarara!!. Even Celty's boyfriend is surprised that they've never considered each other romantically.
Naruto: Homura and Koharu, the two members of the Konoha Council, always make their appearances together. They were teammates and seem to have stayed together through the decades. This could be taken just as the fact that they work together and there has never been a need for a scenario where they appear separately, so YMMV.
Or, they may actually be married. Their relationship, other than teammates and coworkers, has never been explicitly defined.
Okabe and Mayuri have this going a bit in Steins;Gate with Okabe spending most of the series Scrambling to prevent her death to the detriment of some of his other friends, and eventually having to sacrifice even his actual love interest. She gets better though. It is only VERY subtly implied, and could be interpreted as her being used to the kind of remarks Okabe and Daru make when they're being perverted, but there are hints that part of the reason they aren't involved is that she's lesbian.
In Kotoura-san, though Yuriko makes several moves on Dai'chi throughout the series (which he ignored). They're close enough to be practically family, especially since Yuriko lost her mother. Dai'chi's mother practically acted as Yuriko's mother figure.
Azumi Hayakawa and Taro Misaki from Captain Tsubasa, as their relationship mirrored that of Tsubasa and Sanae but without real romantic undertones.
Also Yukari Nishimoto and Kouji Kanda.
Mashiro and Kaya from Bakuman。 have this sort of relationship, made all the more interesting by the fact that Mashiro is partners (both Mangaka partners and Heterosexual Life-Partners) with Kaya's boyfriend and eventual husband.
Makoto and her former schoolmate Ken Shinozaki (the guy who covered her with his umbrella after she had her heart broken under the rain) in the Sailor Moon anime. Usagi even asks her if he's her boyfriend, but Mako denies it and immediately says "our bond is beyond lovers".
Wolverine has this kind of relationship with most of the X-Women, Psylocke and Storm standing out among them. He'll go to amazing lengths to help them, and even harbors a bit of Big Brother Instinct towards any would-be suitors, but when it comes to getting in a relationship with them himself, it just doesn't seem to happen. Fans speculate this is due to his awareness of his own Cartwright Curse.
However Wolverine has pursued relationships with his teammates in alternate time-lines, including marrying Storm in a "What If?" and being involved with her in the war-torn alternate future in Days of Future Past. Not to mention his fixation with Jean Grey.
Nightcrawler and Shadowcat have a similarly close relationship. They did once consider actually dating but decided it would just be too weird (partly due to the fact that she was also involved with Kurt's HeterosexualLife Partner Colossus.)
Modesty Blaise and Willie Garvin in the long-running Modesty Blaise adventure comic strip. As explained many times in the strip, this is due to them sharing a bond that's stronger than love. See the literature section for additional information.
Angel and Faith from Buffy the Vampire Slayer and Angel have become this after the events of Season 8, and now they are sharing joint billing in their Season 9 spinoff comics.
Shirou and Louise, by the end of Hill of Swords. They certainly care deeply for one another, but the relationship isn't the least bit romantic.
Lyra and the titular main character of This is the Life: A Tale of a Human in Equestria give each other massages and have even cuddled in bed together, but aren't the least bit romantic with one another. The way the main character jumps to conclusions in the prequel implies that they do have feelings for each other, but neither of them have really considered it since they're a human and a pony respectively.
Mary and Bert in Disney's Mary Poppins—at the insistence of P. L. Travers, author of the book on which the movie was based. The song "Jolly Holiday" was rewritten at one point to make it clear that there's no romance between them and that they're just very good friends.
Polly Plummer and Diggory Kirke "were always great friends", but neither got married. Polly is referred to by the Older and Wiser Jill and Eustace in The Last Battle as "Miss Plummer", and as we all know Diggory grew into The Professor but never was said to have been married.
Emmeline "Lucia" Lucas and Georgie Pillson, in E. F. Benson's Lucia series. Everyone thinks they've been having an obvious affair for years, but they have never been anything but close friends. In Mapp and Lucia, after Lucia becomes a widow, Georgie is terrified that Lucia will expect him to propose to her, and Lucia is terrified that Georgie will propose to her. They're both quite relieved to find that they agree in not wanting anything more.
Lizzie Bennet and Colonel Fitzwilliam from Pride and Prejudice have great friendly chemistry during their time in Kent (which most likely continues after Elizabeth's marriage to Darcy).
Elinor and Colonel Brandon from Sense and Sensibility. Some of the cast start shipping them, but they happily remain nothing more than good friends and eventually family when he marries her sister.
Matteo and Tzigone grow into this dynamic across the Counselors and Kings trilogy. The two are frequently mistaken for lovers, but while Tzigone does sometimes flirt with Matteo, it's made plain she does it only because he's a dedicated member of a quasi-religious order that's supposed to be celibate and she likes to tease him; their friendship, while both deep and meaningful, is devoid of serious sexual attraction. At one point it's teased that they're actually (half) siblings, but this turns out not to be the case.
Conn and Rowan in The Magic Thief series. Rowan is Conn's best friend who also happens to be his own age, and while Rowan does have a Clingy Jealous Guy who is jealous of all the attention she pays to Conn, the two of them have a wholly platonic relationship without even a hint of Ship Tease. (OK, so they do Sleep Cute once, but that's about it.)
Several instances in The Chronicles of Magravandias due to a lot of arranged marriages. Khaster and Pharinet (though Khaster starts developing other ideas), the emperor and empress, and Valraven and Varencienne. The last pairing is actually perfectly happy in their loveless marriage, believing they function better as friends and allies. And they're both in love withother people anyway.
Camille and Thérèse's marriage in Thérèse Raquin. Thérèse is a lonely, bored woman. Camille doesn't seem to even notice he's married.
The Missus and John-the-dig in The Thirteenth Tale. Vida believes that they'd have been lovers if they'd lived in a different time, but she was older and social conventions got in the way.
Modesty Blaise and Willie Garvin were just as platonic towards each other in the novel series as they were in the comic strip, perhaps even moreso. As explained, this is due to Willie owing Modesty so much that the two of them share a bond that transcends romance. The only time Modesty even kisses Willie on the lips is in the final short story, "Cobra Trap", moments before she dies.
Eventually, Jo and Laurie in Little Women and its sequels. Laurie eventually agrees with Jo's assessment that they're ill-suited to be husband and wife, and while they're both happily married to others, they remain best friends and frequent co-conspirators. Jo is the only one allowed to call him by the pet name "Teddy," and moreover, gave her own son that name.
Maria Huntsman and Victor Medina from Domina. They've been close friends for at least thirty years, and their respective spouses are dead, but they're still just friends. It's to the point that their kids sometimes refer to both of them as their parents (and get embarrassed about it after).
In Piers Anthony's Apprentice Adept series, oaths of friendship "supersede all relationships, conflicting with none, not even the male-female ones." Stile swears an oath of friendship with Neysa, an oath so powerful it draws in an entire pack of werewolves, an entire herd of unicorns (save the Stallion), and the Lady Blue, thereby avoiding a great many unfortunate complications.
Skulduggery Pleasant and Valkyrie Cain. Fanon aside, while they are clearly the most important person in each other's life, there has never been anything romantic between them. He is a several hundred years old skeleton, and she is a 12-16 years old girl. Skulduggery is extremely Papa Wolf towards her, and she once went To Hell and Back for him.
Kel and Neal in Protector of the Small. Neal was Kel's sponsor when she first became a page and became her Lancer later when they both reached knighthood. Although Kel did have a crush on him during her page years, it passed during squiredom.
Mulder and Scully exemplify this trope during the first half of The X-Files. The fact that they eventually get together retroactively turns this into a case of Will They or Won't They?, but for the first four or five seasons, the relationship is portrayed as an intensely close but basically platonic romantic friendship. (Keeping them platonic forever seems to have been the original intention, although Word of God is somewhat contradictory on the subject, but eventually the characters just seemed to have other ideas.)
Buffy the Vampire Slayer: Xander & Willow are like this at least for the first three seasons. They've known each other their whole lives (or at least since kindergarten), and are so close that Xander is even able to save the world at the end of Season 6 by telling Willow how much he loves her. They "dated" as children, Willow had a mostly unrequited adolescent crush on Xander, and have a brief fling as teenagers, but are basically friends throughout.
Zoe and Mal in Firefly; old army buddies who happen to be close enough to give Zoe's husband Wash a fit of jealousy in War Stories. It gets played for laughs at the end of the episode, when Mal and Zoe tease Wash by acting like they're going to kiss, but are actually so reluctant and awkward (and the chemistry so off) that the whole thing falls flat on its face. Summed up in the words of their amoralmercenary teammate Jayne, who walks in on the scene halfway in:
Olivia Benson & Elliot Stabler from Law & Order: Special Victims Unit are partners and very good friends. The closeness of their relationship sometimes causes friction with their colleagues, but never threatens Stabler's relationship with his wife and four (later five) children.
Their relationship does occasionally cause some marital friction. Kathy sometimes finds it difficult to deal with the fact that Elliot confides in Liv instead of her. There are also the unfortunate times when Liv has to be the go-between (when Elliot is undercover and unreachable, for example) and Kathy clearly objects to being kept out of the loop of her own husband's life. Still, it doesn't come up nearly as often as you'd expect and Elliott and Liv really are just friends.
Kathy does seem to have accepted the relationship after she gets back together with Elliott, at one point referring to Liv jokingly as Elliott's "work wife."
Susan and Simon from the earlier seasons of Teachers. She's married for part of the series, but even after her divorce, the pair remain best friends and nothing more.
It seems that Lindsay and Matt are this too in the third season. Then they have a fling in the last episode, and in the first episode of the fourth season, James Lance has left the show and Matt is, apparently, dead. (The show lost a lot of its appeal in the fourth season. And not just because James Lance left.)
Lucas Scott and Haley James Scott from One Tree Hill. Their genuinely platonic friendship was the cornerstone of the show, with Haley eventually becoming Lucas' sister-in-law at the end of season one.
Merlin and Guinevere in Merlin, especially as of season three. They are also part of a Power Trio with Prince Arthur (Gwen has Official Couple status with him, and he and Merlin are Heterosexual Life-Partners), but the two of them basically consider themselves Arthur's guardians, insofar that when Gwen is awaiting execution, she actually tells Merlin: "You'll have to look after him when I'm gone."
Likewise, Arthur is acutely aware of how close they are, and on more than one occasion, has put Guinevere's wellbeing into Merlin's care should anything ever happen to him.
Alice and Jodie from Soap had one of these - both of them were gay but after two of their dates (with nameless people) clashed and they fought, they decided to non-romantically date each other. Until Carol's mother said she wasn't comfortable with her granddaughter (Jodie's daughter) growing up with a lesbian (the show was made in the 70s).
CJ and Toby in The West Wing are shown in flashbacks to have been this before the Bartlet campaign. During the main timeline of the show, their True Companionship with the other members of the senior staff dilutes their exclusiveness somewhat, but they remain best friends and special confidants, with CJ being the only person who can call bullcrap on Toby's antisocial facade and Toby being the only person who isn't intimidated by CJ's habitual aggressiveness.
Lisa and Ray from Sister Sister. They're thrown together when they discover that Lisa's adopted daughter and Ray's adopted daughter are twins, and the girls naturally want to be together. Lisa and Ray have very clashing personalities, but they're (usually) good at working together to raise their daughters and eventually form a friendship.
Subverted by Lennier and Delenn in Babylon 5. But not until almost the last episode.
Played straight with John Sheridan and Susan Ivannova. Good friends for roughly thirty years and not one hint of tension or romantic jelousy between the two.
Bernard and Fran in Black Books, who stay together because nobody else can stand either of them. Apparently, there is some way-back romantic history, but Bernard says he's not allowed to remember that.
Liz and Jack on 30 Rock. In the episode where they accidentally get married, Mr. Weinerslav describes this trope nearly word for word.
Weinerslav: Have you spent time with each other's families? Have you attended special events together, such as class reunions, birthday or holiday celebrations, weddings or extended car trips? Are you each other's emergency contacts? Do you even drink together at work, perhaps while summarizing what you've learned over the day or week? Have you shared intimate details of your fears, hopes, and dreams, both personal and professional? Is this the longest and perhaps most meaningful relationship in your life? Do you often find yourselves thinking the same thing and then saying it at the exact same time?
Benjamin Sisko and Jadzia Dax from Star Trek: Deep Space Nine. Their friendship is a bit more complicated than this trope, however, since they were also friends back when the Dax symbiote was in a man's body. So while they were this trope during the show, they started out as Heterosexual Life-Partners.
In Warehouse 13, Pete and Myka are like this , even thought they both think that the other is attractive, Pete even tells Myka at one point that he thinks she is beautiful, and they care about each other they aren't interested in being with each other. Myka once describes Pete as her "big brother."
Actively invoked in Doctor Who when after having travelled with Rose and Martha, the Doctor specifically says that he's only looking for a friend when Donna joins him. (Rose was someone he'd bonded with to the point of it seeming romantic at times, especially with how losing her affected him for a long time, and Martha had been in love with him but he, being the Doctor, didn't notice, and she eventually left because she realized he wasn't capable of returning her feelings.)
Shipping aside, the Doctor has this sort of relationship with most of his female companions.
Notable examples include the Fourth Doctor and Romana, the Tenth Doctor and Donna Noble (as mentioned above) and the Eleventh Doctor and Amy Pond (once she got over her childish crush).
Don't forget the Doctor and the TARDIS; probably the truest form of Platonic life Partners in the show. Friends may come and go but the TARDIS is forever!
If you want Ship Tease, you want the Doctor and the TARDIS, if anything. He once hugged it after being separated from it for a time. And of course there is the entirety of the episode "The Doctor's Wife." The title refers to the TARDIS.
And Sarah Jane asking Rose, "Does he still stroke bits of the TARDIS?" Rose laughs and says, "I'm like, do you two want to be alone?"
Tom and Julia, musical writing partners from Smash.
Veronica Mars and Wallace Fennell. They're best friends, confide in each other about (almost) everything, and spend an inordinate amount of time together. However, neither of them ever shows any romantic interest in the other and they both date other people.
Danny and Jackie in Blue Bloods are like this. Danny is Happily Married and Jackie dates elsewhere; on one episode Danny actually questioned her suspiciously about her dates as if he was a big brother. Linda, Danny's wife seems to trust Danny and Jackie together.
Peggy and Miranda are both this to Declan in Mysterious Ways. There is ship-teasing for both pairings but Declan's only relationship in the series is with a different woman and neither relationship gets upgraded.
Boomer and Mikayla from Pair Of Kings to the point where he goes against the bro code and tricks Brady just to hang out with her. Boomer even looks like Mikayla's ex-boyfriend. However, they've shown no romantic interest in each other.
Will and Diane in The Good Wife: the most functional relationship on the show by far- to the point of platonically slow dancing in glee.
Phoebe and Joey from Friends. They playfully flirt, they have a softness for each other (often both of them picking the other over the rest of the group), they are really close friends with a lot of Ship Tease, including at least four kisses, yet they never dated (or had sex) in all ten years, and aside from their jokes about being a possible couple in the future, it was clear that they just wanted to be friends, but nothing more.
Mr. Carson and Mrs. Hughes, the butler and housekeeper respectively, of Downton Abbey. Which does not, it must be said, prevent them from being theFan-Preferred Couple of the show.
Annie and Abed on Community are heading towards this. They are often the only ones not to be put off by the other's quirks, they live together and they have even kissed passionately once. This is mostly due to Abed's indifference to relationships. Admittedly it doesn't get as much attention as Troy and Abed.
Ted & Robin in How I Met Your Mother. They dated for a year but decided to go their separate ways. Since then they've become extremely close to the point of living together and Ted being her emotional support through most things.
Clark and Chloe in Smallville. They were initially good friends, but became much closer as the seasons went on and she played a far more active role in his journey to becoming Superman. By the later seasons, they are firmly Like Brother and Sister, view each other as family, and actively serve as Shippers on Deck for each other's relationships (Clark becomes a Shipper on Deck for Chimmy, and later Chlollie, and in both cases his Big Brother Instinct compels him to make sure everything was alright in Chloe's relationships, and Chloe becomes a Shipper on Deck for Clois, repeatedly hinting to Clark and Lois that she thinks they have relationship potential). They also develop a strong working relationship, with Chloe serving as Mission Control for the entire Justice League of America, and Clark working in the field as a superhero.
Kurt and Mercedes and later Kurt and Rachel from Glee.
Criminal Minds has, most prominently, Derek Morgan and Penelope Garcia. The two of them very openly and casually flirted with each other, especially in the earlier seasons, but this never reached anything other than the "playful" stage. However, the two of them do share a genuine platonic love for each other, as evidenced in "Penelope" when Morgan takes up temporary residence in Garcia's house in order to protect Garcia from her would-be killer from the episode before. It's also been implied by the fandom that Prentiss and Reid and Prentiss and Hotch share similar roles, and the show has characterized JJ and Reid (with varying success) as this.
Dutch and Claudette from The Shield have their issues, but will always have each other's backs. Dutch's happy ending in the series finale is Claudette finally admitting Dutch is her best friend.
Sherlock Holmes and Joan Watson in Elementary. They get off to a rough start at first with Joan being Sherlock's sober companion, but soon grow into equal partners in solving crime.
This trope was even the foundation of Their dynamic as the writers wanted to show that men and women can be close friends and work together without ever forming a sexual relationship.
Teyla has this dynamic with Sheppard, Rodney, Ford, and Ronon on Stargate Atlantis. In Sheppard's case, there were massive amounts of Ship Tease, but after Teyla gets pregnant, their dynamic soon settles into this. She even names her son Torren John after her father and Sheppard.
Red and Ted from Red & Ted's Road Show, who will cheerfully go across the country and blow everything up together.
Eliza: What I done - what I did was not for the dresses and the taxis: I did it because we were pleasant together and I come - came - to care for you; not to want you to make love to me, and not forgetting the difference between us, but more friendly like.
In many of the adaptations (including the musical My Fair Lady), it's suggested that they do get together at the end - although even then, it's rather ambiguous.
Banjo and Kazooie, the two main characters from the videogame aptly titled Banjo-Kazooie, are an example of this trope, as one is a male and the other is a female, but they do not persue a romantic relationship, choosing instead to be close friends.
It probably helps that Banjo is a bear and Kazooie is a bird.
In Persona 3 Portable, a female MC shares this sort of relationship with Junpei. Despite knowing her the longest, he's the only male member of SEES who can't become a love interest. Mostly because he already had a in-game love interest. Dummied Out dialogue implies that at one point he was to be a love interest though.
In addition, there is Mitsuru and Akihiko. While they've been friends well before the start of the game and clearly trust each other more than anyone else, there's nothing in-game implying that the two of them are romantically interested in each other. In Mitsuru's Social Link, she even states that Akihiko is nothing more than a teammate and a close friend.
In Dragon Age II, both Aveline and Varric serve as this to Hawke, depending on the gender, since they're the only non-family party members who cannot be romanced aside from some playful flirting. In Aveline's case, she later develops a relationship with a fellow Guardsman. Varric it seems is comfortable with just being Hawke's friend, and of course he has Bianca.
Chris and Jill of the Resident Evil series are depicted as this, especially in Resident Evil 5 with Chris angsting over Jill's apparent death for much of the game. This turns out to be a major plot point in the story, as the possibility of her being alive is what drives him to push forward despite orders to retreat. After the number of games they've been in together, (only one each where they were separate) they are more or less inseparable in fandom eyes. Whether or not there are romantic feelings involved has not been addressed either way, and Revelations only lampshade hangs as to whether or not they are Platonic Life Partners or Battle Couple. They're one of the cases where it's very hard to tell whether things like Sleep Cute are meant as moments of Like Brother and Sister or as Ship Tease.
Sheva tries to coax a straight answer out of Chris during a conversation in part 5 by noting how fondly he seems to remember Jill, but Chris simply replies "We were partners." Gee, that helps.
Jessica in Revelations also brings up similar dialogue, with Chris explaining that "it's all about trust.". Right.
The original Link, from the firsttwo games, has two Zeldas on his hands. Considering one gave him a big kiss after saving her from an ancient curse and the other only said "Thanks" after he'd saved her from Ganon, I think we can say he's the only Link to be at once platonic friends and more than friends with Princess Zelda.
In Fire Emblem Awakening, a female Avatar and Chrom have this sort of relationship if they don't get married to each other. Chrom's daughter from the future, Lucina, even suspects the two of them are having an affair in her early supports with the Avatar. They aren't.
If a guy and a girl who can potentially marry reach "only" an A support level, they can be seen as this fairly easily. The closest to an exception would be Gregor and Cordelia, as their A support makes their relationship a Matchmaker Crush from his side.
In Hunted: The Demon's Forge, female elf archer E'lara and male human warrior Caddoc are close friends who have made a career out of adventuring together. Despite their closeness and the fact that they're both (presumably) single, no romance is ever implied between the two.
Kyo Kusanagi and Athena Asamiya are hinted to have become this in The King of Fighters, Athena's slight crush on Kyo notwithstanding. In the KOF: KYO manga their interactions become more platonic than anything after Iori Yagami attacks Kyo at school and both Athena and Kyo's girlfriend Yuki attempt to stop them; later in the KOF: KYO game, Athena gives him pep talks about "the female heart" which are direct allusions to Yuki, and isn't happy if you make Kyo hit on her instead. In the KOF 2000 CD drama, when Athena manages to contact Kyo after much effort, Kyo tells her he can't go back home and even asks her to relay a message from him to Yuki before leaving. And finally in KOF XIII, if you have Athena talk to NESTS!Kyo about how he shouldn't take all responsabilities since his friends support him, he will directly ask her if Yuki was the one who told her to tell him this.
Kyo might have these dynamics with his fellow Sacred Treasure Team member Chizuru Kagura as well, considering how she's a sort-of mentor to him in KOF:KYO and how pissed off he is at Ash Crimson for stealing her powers.
In Katawa Shoujo, when you-as-Hisao unlock a path, the best friend of the girl who was chosen as a love interest might become this to Hisao himself. Specially obvious in Hanako's route (where Lilly and Hisao team up to give her a birthday party with disastrous consequences) and in Rin's (where Emi and Hisao discuss Rin's Cloud Cuckoo Lander mindset) Subverted in Shizune's path: you can have Hisao give Sex for Solace to Misha, but that leads to Shizune's bad ending, and it turns out Misha was in love with Shizune and not him anyway.
Akira and Mika from Lux-Pain. They are extremely close friends to the point that everyone thinks that they'll end up together. However, Akira sees Mika Like as a little sister and Mika considers him someone to beat up and torture. This relationship is questioned however when Mika is targeted by the serial killer and Akira goes to extreme lengths to save her. Near the end of the game though, you can't help but notice that Mika seems more interested in Shinji than Akira himself which is why their relationship romantically is never brought up again. As for Akira, the characters thinks he has it in for the main character Atsuki.
Phoenix "Nick" Wright and Maya Fey from Ace Attorney. They go through a lot togheter, and Phoenix will go to hell and back to help her if she's in trouble. It's implied they still keep in contact after they go their separate ways between the events of Trials and Tribulations and Apollo Justice. This is later confirmed in Dual Destinies.
Apparently the case with Ikuko and Tooya Hachijō in Umineko no Naku Koro ni. By the time of the epilogue, they have lived together for decades and are both the most important person in the other's life (at least in we consider "Tooya" to be a completely different person as Battler), but they aren't married and don't seem to be in a romantic relationship. That's actually the first thing Ange asks them when meeting them.
Rachel and Baam from Tower of God. She taught him everything she knew and visited him everyday, whereas he absolutely idolizes her. Then, she disappears into the Tower. Baam follows her into the unknown, repeatedly risking his life on minimal odds. But romance, even though some people like Androssi and Yuri try to see it that way, was never a part of their relationship. When Baam found her, things got a little sour, though.
Roy and Haley from The Order of the Stick. After Roy falls to his death during the siege of Azure City, Haley becomes the team's leader. Doesn't help that aside from him, Haley's the only sane person left.
Marten and Faye in Questionable Content. They moved in as roommates early in the series and the romantic tension created a case of Will They or Won't They?. Later on though, the two talk it out and decide not to date each other and instead turn their relationship into a very close friendship.
Bactine from Lin T thinks she and Xylic have this (but he's just really good at hiding that he is in love with her).
Living with Insanity has David and Alice. Apparently she was based off an old girlfriend he's still friends with.
In Homestuck, troll culture has a relationship quadrant especially for this (moirallegiance).
Equius and Nepeta are used as an example of a perfect moirallegiance in action because they are two ends of a spectrum and balance each other out very well, and Equius clearly thinks of Nepeta in the same way he would a little sister.
Another example of complete moirallegiance is Karkat and Gamzee, especially showcased when Karkat stops Gamzee's killing spree.
In Chimneyspeak, Alice and Elgie have known each other since Alice was a teenager and, despite the bad blood that occasionally crops up, are about as intimate as a man and woman can be without actually being...intimate. Subverted at the very end of the comic when they actually do start having sex.
Jack and Lori from The Insane Quest has been friends since teenagers and, apart from once comment made by Jack early on, there has been no implications of romance between the two.
Karen and Ralph from The War Comms, so much that the idea of them as a couple grosses both out. Molly sees her relationship to Syrius as this, too.
Brian Phelps & Jill Whelan, hosts of The Brian And Jill Show, dated initially but the relationship did not develop and they have instead become the best of friends. In fact, Jill was originally slated to replace Brian's retiring co-host from The Mark & Brian Radio Program and, when that didn't work out, they took the podcast route.
They actually have this sort of friendship in a few different universes, including the main Marvel 616 universe, where they've been best friends and thicker than thieves since the 80's.
A number of characters have relationships like this in the show. Iceman and Jubilee also count, as they spent almost all of their screen time during season 2 together, always went along together on wacky hijinks, and seemed practically inseparable. Scott and Jean, prior to their actual getting together, had shades of this as well, but we knew from the beginning they wouldn't stay that way.
Kate Winslet: "Before we met, I thought, 'I'm just going to fall completely in love with this guy.' Once I met him, I thought, 'Well, it's true. Leonardo DiCaprio is incredibly beautiful, but no way.' He's just so normal and so — what's the word I'm looking for? — fundamental. Very chatty and so funny that we laughed and joked around. Everybody kept saying, 'God, you two just get on so well'. Leo and I sometimes still talk about it and say, 'Oh, should we have an affair just for the hell of it?' But we wind up agreeing, 'No, we couldn't, because we'd laugh too much.' We just wouldn't be able to take it seriously."
Danny Pudi and Alison Brie from Community have this type of relationship in common with their characters.
Tori Amos and Neil Gaiman. They reference each other constantly in their work and she says she views him as being like a brother. Both are happily married with families and are simply extremely close friends.
Carrie Brownstein and Fred Armisen, co-creators of Portlandia. Of their relationship, Brownstein said, "Sometimes I think it’s the most successful love affair either of us will ever have."
Gwyneth Paltrow and Robert Downey Jr of the Iron Man series. Just watch a panel with those two.
Jennifer Lawrence and Josh Hutcherson from The Hunger Games. They're best friends and adorable with each other. Summed up in this article 
Mick Fleetwood and Stevie Nicks. They briefly had an affair but it didn't last. Stevie has often said she considers him her best friend and he asked her to be godmother to his children.
Vincent D'Onofrio has said this is the relationship between himself and Kathryn Erbe, who played his partner on Law & Order: Criminal Intent.
Comedians Ron White and Kathleen Madigan; they are extremely similar in their comedic timing and subject matter, constantly go on tours together, and have been close friends for decades.
John Wayne and Maureen O'Hara, for one of Classic Hollywood's best-known examples. They have such strong onscreen chemistry in films like The Quiet Man and McLintock that even today, many viewers assume they were husband and wife off-screen.