Sibling Team



Two (rarely, more) blood siblings of either gender working together as equal partners. Their business often involves ass-kicking, in which case they are likely to be Bash Brothers as well. The easiest way to tell that a sibling duo fits this trope is when they are most commonly referred as "the Surname brothers" or "the Surname sisters".

Brother-Sister Team is a gender-specific subtrope. Related tropes are Badass Family (for when the whole clan is in on the ass-kicking), Super Family Team (when the whole clan has superpowers), Unrelated Brothers (a Sibling Team in professional wrestling), and Wonder Twin Powers (for twins with superpowers that only work in concert). Contrast Cain and Abel.

Anime and Manga

 * The Elric brothers from Fullmetal Alchemist. They are state alchemists. Even if Al is not officially a state alchemist, they are working together as equal partners on both government missions and their personal quest for the Philosopher's Stone.
 * Also the homunculi in the manga are all brothers and sisters.
 * Xia Yu sisters from Full Metal Panic!: assassins/spies. Also, Creepy Twins.
 * Kouji and Tetsuya from Mazinger Z and Great Mazinger are adoptive brothers and Humongous Mecha pilots. When they are actually fighting their enemy instead of each other, they are a force to be reckoned with.
 * Tetsuya and Jun from Great Mazinger are also adoptive siblings. They overlap this trope with Battle Couple.
 * Duke and Maria from UFO Robo Grendizer.
 * The Thompson Sisters (possibly named for both the machine gun and the Thompson Twins) from Soul Eater. In their backstory they were criminals, until they met Death The Kid and became his partners.
 * Recent developments might see Liz and Patti working together as meister and Weapon, as Kid is currently imprisoned by Noah.
 * Confirmed in the Salvage arc. Patti is shaping up to be a menace as Liz's meister.
 * Gaara, Kankuro, and Temari of Naruto, who are sometimes called the Sand Siblings by the fandom, after their hometown. Early on in the series, they were actually closer to a deconstruction of this trope; Temari and Kankuro were both out right terrified of Gaara and only followed him out of a mix of obligation and fear. It isn't until post Time Skip that they start following the spirit of this trope.
 * N2R from Magical Girl Lyrical Nanoha, a unit made up of four of the Sisters, namely.
 * Also, the Liese Twins from A's, although they are twin familiars rather than a real family.
 * Natsumi and Kurumi in the Ranma ½ OAV, The One To Carry On. The former uses a rug beater to project razor-sharp freezing winds, while the other uses a hair ribbon several yards long to channel burning ki. The two sisters even have a Finishing Move Combination Attack that uses both aspects to blast their enemies away.
 * From the late manga, the sisters Pink and Link, who nearly poisoned the entire town.
 * In the anime, Shampoo's childhood friends Rinrin and Ranran.
 * From the first movie, the brothers Daikokusei and Daihakusei of the Seven Lucky Gods.
 * As a note, the three previous Sibling Teams are all twins. Seems like you can't be twins in this series without being part of a battle team.
 * Oishinbo: The brothers in the Ramen and Gyoza volume.
 * The Hitachiin brothers from Ouran High School Host Club are more or less inseparable twins and often partners in crime. They've also been shown beating up punks together.
 * Prowl, Sideswipe, and X-Brawn in Transformers: Robots in Disguise.
 * The Frost Brothers of Gundam X are twins with a Psychic Link that enables them to communicate telepathically no matter how far away from each other they are.
 * Gundam has more. There's The Zabis,, Kira and Cagali and Team Trinity.
 * Fairy Tail gives us 'Demon' Mirajane, Elfman, and Lisanna, but the team presumably breaks apart with the latter's death and Mirajane's retirement to Team Mom.
 * The are an example of Wonder Twin Powers.
 * Ikki and Shun from Saint Seiya at first started off as Cain and Abel. Finally in the last movie, Tenkai Hen~ Overture, they finally worked together.
 * If you go by the manga, you could say that this had been happening for a long time since all the bronze Saints are half brothers with Shun and Ikki being the only full-brothers of the group.
 * Panty and Stocking from Panty and Stocking With Garterbelt
 * The Kongo Twins of Eyeshield 21, though Agon gets far more attention then Unsui. There's also the Gonzales brothers of the Nasa Aliens.
 * The Pichu Brothers in the Pokémon anime.
 * Magikano
 * Gedou Otome TailThe Borden Twins i
 * The eponymous characters from Chinese anime Gourd Brothers. Seven brothers born from seven gourds on the same vine, each have one color from the rainbow. Rainbow...

Comics

 * Spider Girl plays with this a LOT. Fitting for a 'verse made up of Legacy Heroes.
 * Crazy Eight and Funny Face, a villainous example.
 * May also teams up with two annoying younger kids in spider costumes, but she's not really related to either of them.
 * However, there is  and , both of whom she's worked with.
 * The Brothers Grimm also fulfill the role as well, as villains, of course.
 * Hawk and Dove, at least the original Hall brothers.
 * During the rare periods when they're both alive, sane and in the same reality, Northstar and Aurora of Alpha Flight serve as a sibling team.
 * Cyclops and Havok of the X-Men have attempted this on occasion. It never lasts long.
 * Joe, William, Jack and Averell Dalton in Lucky Luke.
 * The Double Dare sisters from Nightwing
 * Power Pack: Four siblings—two boys and two girls.

Fanfic

 * Pretty Cure Perfume Preppy: Chloe/Cure Rosa and Chiarra/Cure Vanilla are sisters.

Film

 * Joliet Jake and Elwood Blues AKA The Blues Brothers.
 * The creepy albino twins from The Matrix sequels.
 * The clone army from Star Wars could be an example. All the clones grow up together, at any rate, and individual troopers have other troopers that they are especially close to. If not, the four-man commando squads, as in Republic Commando, definitely count.
 * Trinity and Bambino, the "right and left hand of The Devil", respectively, in the Trinity series of Western films (played by Terence Hill and Bud Spencer, no less). Though Bambino isn't particularly happy about having a brother like that, they make one hell of a team when they join forces.
 * in The Prestige, who live their lives as one person for the sake of their magic act.
 * From Transformers: Revenge of the Fallen, we got the sisters Arcee, Chromia and Elita-1.
 * Skids and Mudflap count too. Two twins who help each other and the Autobots to fight the Deceptions, Simmons against Devastator and help Sam to revile the Matrix...when they don't argue with each other.
 * The Bagrov brothers from Brother, but especially the second movie.
 * The Mercer brothers, full stop.
 * Turk and Virgil Malloy from Ocean's Eleven.
 * The Stabbington brothers in Tangled.
 * Connor and Murphy McManus, The Boondock Saints.

Literature

 * Hardy Boys.
 * The Weasley Twins and their joke shop from Harry Potter.
 * And in the Final Battle,.
 * Dennis and Colin Creevey.
 * The Geste brothers in Beau Geste.
 * If clones count, the so-called Devist family, that sleeper cell of cloned Imperial pilots who become Farm Boys, and are insular and very close because of Cloning Blues and Fantastic Racism.
 * In Young Jedi Knights, the Solo Twins Jacen and Jaina. Once they're out of their teens they quickly stop being together all the time, and, well, we know how it ended.
 * The Pevensies, the main characters of the first series of books of the Chronicles of Narnia are brothers and sisters, until Susan and Peter opt out and cousin Eustace comes in.
 * Phury and Zsadist from the Black Dagger Brotherhood.
 * The Brothers Majere in Dragonlance, at least, to start with.
 * The sons of Fëanor from The Silmarillion.
 * And Elrond's twin sons, who get very little mention in the Lord of the Rings main trilogy.
 * Rory and Coco in Little League Family. Rory catches and Coco pitches. As pitcher-catcher are almost a subteam in baseball, that makes them a literal as well as metaphorical team.
 * The Swallows and Amazons series is mostly about multiple Sibling Crews interacting with each other.
 * Most Enid Blyton protagonist groups are at least partially family-based. The Famous Five consist of three siblings, their cousin and her dog, the 'Adventure' group are two pairs of a brother and a sister, etc.
 * Teucer and Greater Axaj in The Iliad. They're half brothers, with Teucer being the bastard.
 * Georgia and Shaun Mason in Mira Grant's Feed are adopted, but every bit as close as blood siblings (they don't like to be apart, ever). They work together on their blog network and watch each other's backs when they go into infected zones.
 * Monza and Benna in Joe Abercrombie's Best Served Cold make a very efficient Sibling Team—he's the people person, she's the one who fights. Together, they lead a band of mercenaries. It's implied that they are closer than most siblings.
 * Half-brothers Harry Dresden and Thomas Raith in The Dresden Files, wizard and vampire respective.
 * Niko and Cal Leandros. They even have a monster hunting agency.
 * From A Wrinkle in Time, there's Meg and Charles Wallace Murry. Plus Calvin O'Keefe, who just gets pulled along for the ride and isn't related to the Murrys.
 * Same goes for Sandy and Dennys, the Murry twins in "Many Waters."
 * Sabrina and Daphne, the eponymous heroines of The Sisters Grimm.

Live-Action TV

 * Brothers A.J. and Rick from Simon and Simon.
 * The Winchester brothers from Supernatural.
 * Green Acres had the Monroe Brothers (Alf & Ralph): general contractors. Alf was a man, Ralph was a woman.
 * The Halliwell sisters (a trio) from Charmed.
 * Don and Charlie Eppes work together to pursue evildoers on Numb3rs. Don is an FBI agent and Charlie is a Smart Guy math consultant.
 * Justin, Alex and Max in Wizards of Waverly Place.
 * Damon and Stefan Salvatore occasionally team up on The Vampire Diaries.
 * Hank and Evan in Royal Pains.
 * Frasier and Niles Crane automatically team up for anything; from schemes to snag Frasier a date to elaborate, convoluted escapades that end up with them both being accidentally arrested for murder. The fact that they meet at least once a day to complain about their problems and beg the other to help them out contributes to this greatly, while neither the fact that their Sibling Rivalry frequently interferes with their teamwork, nor several dozen chewing-outs from their father for blowing things, has never stopped them.
 * From Super Sentai and Power Rangers:
 * Geki, Tyranno Ranger and his older brother Burai, Dragon Ranger from Kyouryuu Sentai Zyuranger.
 * Mahou Sentai Magiranger, with five siblings. Western version Power Rangers Mystic Force reduces it to Vida and Madison, the Pink and Blue Rangers.
 * Power Rangers Lost Galaxy: Leo, the Red Ranger, and Mike, the Magna Defender. Same for Seijuu Sentai Gingaman with Ryouma, GingaRed, and Hyuga, the Black Knight.
 * Kyuukyuu Sentai Go Go Five, whose team is also made up entirely of five siblings. Power Rangers Lightspeed Rescue instead has Dana the Pink Ranger and Ryan the Rangers-exclusive Titanium Ranger.
 * The Gouraigers (Ikkou and Isshu Kasumi) from Ninpuu Sentai Hurricaneger and the Thunder Rangers (Blake and Hunter Bradley) from Power Rangers Ninja Storm. (The latter two were both adopted by the Bradleys, but that doesn't matter in the slightest.)
 * GekiBlue and GekiViolet (Retsu and Gou Fukami) from Juken Sentai Gekiranger. Not carried over to Power Rangers Jungle Fury because Theo and RJ as siblings...?
 * Subverted in Power Rangers Zeo: It's heavily implied that Tommy's half-brother David is the Gold Ranger. He isn't. It's also teased that he will assume the powers. He doesn't.
 * The Hoshikawas of Chikyuu Sentai Fiveman were the first five-sibling team, before either GoGoFive or Magiranger.
 * The Amazing Race has one or two of these per season.
 * Minutemen The Made for TV Movie features a team of just brothers.
 * DG and Azkadelia in Tin Man
 * The 1985 Tokusatsu series, Kyodai Ken Byclosser. The eponymous heroes are sibling team consisting of two brothers, Ken and Gin.
 * Half-sisters Morgana and Morgause from Merlin. An Aversion with Morgana and Arthur, as by the time they realize they are half-siblings, they are estranged.
 * Gunther and Tinka from Shake It Up.
 * The three Twist kids in Round the Twist frequently team up to solve the secret to the latest supernatural event in Port Niranda, although in some stories only one character is caught up in the weird goings-on.

Music
Musical siblings are common in rock bands and vocal/R&B groups. Family-based groups are more common in country and older vocal groups. Some examples:
 * Van Halen
 * The Kinks
 * The Beach Boys
 * Oasis
 * The Black Crowes
 * The Andrews Sisters
 * The Carter Family
 * Sepultura (the Cavalera brothers, who went on to form The Cavalera Conspiracy)
 * Veruca Salt (original members Nina Gordon and Jim Shapiro were sister and brother)
 * ACDC
 * Hanson
 * Kings of Leon
 * Evile
 * Lamb of God
 * Heart
 * Gentle Giant
 * The Everly Brothers
 * The Veronicas
 * Remedy Drive is made up of four brothers: Daniel, David, Philip, and Paul Zach.
 * Los Lonely Boys are three brothers.
 * Mary Mary (an Rhythm and blues/ Gospel group).
 * Tom and Bill Kaulitz of the German band Tokio Hotel form two of the four members.
 * Gerard and Mikey Way of My Chemical Romance are brothers.
 * Madina Lake has identical twins Nathan and Matthew Leone.
 * Another set of identical twins are Benji and Joel Madden from Good Charlotte.
 * Nickelback

Professional Wrestling

 * The gimmick of identical twins who can win matches because they look so much alike they can switch places in the ring without their opponent realizing it is a very common one.
 * Ron and Don Harris, who worked both in WCW and WWF under various gimmicks including The Blu Brothers, the Disciples of Apocalypse, and Creative Control.
 * Brie and Nikki Bella, current WWE divas
 * The Shane Twins, best known as The Gymini in WWE.
 * Shu and Kei Sato, two Japanese wrestlers whos gimmick changed from pop singing sailors to Hindu occultists..
 * Matt and Jeff Hardy.
 * Raymond and Jacques Rougeau.
 * Carlito and Primo Colon.
 * The Steiner Brothers.
 * Harlem Heat (Booker T and Stevie Ray)

Religion and Mythology

 * A common trope in pre-Columbian America involves twins doing this.

Tabletop Games

 * Naestra and Arahan, the twin Wood Elf sisters in Warhammer Fantasy who shoot people with their longbows from dragonback.

Video Games

 * The McCall brothers from Call of Juarez: adventurers and robbers.
 * The Chang brothers from Vampire Bloodlines: guardians of Ankaran Sarcophagus.
 * The Kasuga Family of Arcana Heart, four Miko sisters that fight together with Maori as head.
 * Mario and Luigi, the Super Mario Bros.!
 * Who may, or may not be twins.
 * They are, just dizygotic.
 * Terry and Andy, the Bogard Brothers.
 * The Komodo Brothers from the Crash Bandicoot series, though they only appeared together in Crash 2 and Crash Bash, while Joe went it alone in Crash Team Racing. Neither has been seen since.
 * From Final Fantasy X, we have the Summoner Issaru, along with his two younger brothers as his Guardians.
 * J.C. and Paul Denton in Deus Ex and its sequel.
 * Billy and Jimmy Lee, the Double Dragons.
 * In the arcade version of Double Dragon 3, this trope is invoked literally by having the playable characters divided into four groups of different sibling teams (the Lee Bros., the Oyama Bros., the Urquidez Bros., and the Chin Bros.), essentially an excuse to allow more than one player to control the same character.
 * Billy and Jimmy's counterpart in River City Ransom were named Randy and Andy. Their counterparts in the Kunio-kun series were named Ryūichi and Ryūji Hattori.
 * Oscar and Emile Bielert from Valkyria Chronicles, both snipers.
 * Yun and Yang from Street Fighter III.
 * The Great Giana Sisters.
 * The Blue Bomber and his red brother from the Mega Man series, made an actual team as of 10.
 * Faylen and Faylon from Suikoden V.
 * Kat and Ana from the Wario Ware series.
 * The Finito brothers from Max Payne: gangsters.
 * Jao and Mao, the twin co-leaders of the Tenkou Pirates in Skies of Arcadia.
 * Dante and Vergil from Devil May Cry.
 * Palom and Porum are two little twins who team up with the hero in Final Fantasy IV.
 * Sisters Faris and Lenna from Final Fantasy V.
 * Edgar and Sabin Figaro from Final Fantasy VI. Royal siblings, no less. Having them in the same team together is only mandatory for one very brief period, but their most significant scenes involve both of them. Amusingly, while Sabin can be recruited before Edgar in the World of Ruin, but because he's optional, the (mandatory) scenes for Edgar's recruitment leave him mostly silent. You'd think he'd have some comments about his brother's Paper-Thin Disguise, but no.
 * Asbel Lhant and Hubert Ozwell.
 * Hawke and his or her twin siblings are quite capable in battle, and the surviving twin will always have a class that compliments Hawke's, also making them Sword and Sorcerer.

Web Original

 * Hamper and Damper are twin brothers with different psychic powers in the Whateley Universe. One can cloud minds, the other can suppress powers.
 * Red vs. Blue has the Freelancers North- and South-Dakota, who are twins and, according to South, always put together in a team.
 * Doug and Rob Walker of That Guy With The Glasses though Rob usually works behind the camera. He's still credited, mentioned and even shown a couple of times in the videos.
 * John and Hank of Vlog Brothers, who are a real-life sibling team.
 * My Brother, My Brother and Me with Justin, Griffin, and Travis McElroy
 * Epic Rap Battles of History has featured the Wright Brothers vs. the Mario Brothers.
 * Epic Rap Battles of History has featured the Wright Brothers vs. the Mario Brothers.

Web Comic

 * The siblings, Fudge, Batter and Mix Cakea of CAKE are this.
 * Kavra and Khevresh from Wayfarer's Moon. This does not end well when.
 * The eponymous heroes of Nip and Tuck are implied to be this, especially here.
 * Bill and Barry Heterodyne from the backstory of Girl Genius.

Western Animation
"Lester: "Thanks everybody, but I couldn't have done all this without the help of my brainy sister Eliza.""
 * The new Jonny Quest has the Daughters of Zim.
 * Taz-Mania had the Platypus Brothers: general contractors.
 * The Powerpuff Girls.
 * Sonic Underground had a version of Sonic who had a sister and a brother, all on a quest to find their mother.
 * Sunstreaker and Sideswipe of Transformers Generation 1.
 * Twins Jetfire and Jetstorm in Transformers Animated.
 * Lifty and Shifty from Happy Tree Friends.
 * The Duck Brothers in Courage the Cowardly Dog.
 * "GO TEAM VENTURE!"
 * Dave, Fang, and Candy from Dave the Barbarian
 * Team Go was a five-sibling team in Kim Possible. At least until Shego became a villain
 * The Trix in Winx Club are a villainous version.
 * XJ-9 and her robotic "sisters", XJ Mark 1 through 8, on My Life as a Teenage Robot. (They're actually prototypes of Jenny herself, but possess independent personalities and abilities.)
 * In Avatar: The Last Airbender, Sokka and Katara.
 * Zuko and Azula during the season 2 finale, but this one is… unstable.
 * The Legend of Korra has Mako and Bolin, Earthbending and Firebending brothers who make up two-thirds of the show's Power Trio.
 * The eponymous four Teenage Mutant Ninja Turtles display their siblinghood Turtle Power.
 * Más y Menos of Teen Titans animated.
 * The Simpsons: Bart and Lisa whenever they fight Sideshow Bob, or help Krusty.


 * Wild Kratts has the Kratt Brothers Martin and Chris.
 * Real life example too as they both worked together on nature shows Kratts' Creatures and Zoboomafoo.

Real Life

 * Strugatsky Brothers: the most popular Soviet sci-fi authors.
 * Wachowski siblings: the people who brought you The Matrix... and a couple other movies.
 * The Coen Brothers.
 * The Wayans Brothers.
 * The Sherman Brothers, who, among other things, wrote the songs for Mary Poppins and Chitty Chitty Bang Bang.
 * Saints Cyril and Methodius, the creators of the Cyrillic Alphabet, were the youngest and the oldest among seven children their parents had. Cyril was a Teen Genius, Methodius was a military general.
 * James Brothers: Jesse and Frank James, famous American outlaws and leaders of the James-Younger Gang.
 * The James brothers seem to have made a habit out of working with sets of brothers as well. The James-Younger gang included the four Younger brothers: Cole, Jim, John, and Bob. Later the James brothers worked with the Ford brothers: Charlie and Robert/Bob. That didn't work out so well for Jesse though (or, for that matter, the Fords).
 * The Youngers were also cousins to the Dalton brothers, Bob, Gratton and Emmett.
 * The Kelly Gang consisting of brothers Ned and Dan (and two other close friends of the family) were part of an Australian outlaw gang (referred to as 'bushrangers'). Unfortunately Dan tends to get the Second Banana status while Ned was immortalised as a hero who stood up to police corruption.
 * The Wright Brothers.
 * The Marx Brothers.
 * Diector Sam Raimi, who often casts his brother Ted Raimi in his films. Ivan Raimi, also Sam's brother, was one of the screenwriters on Spider-Man 3.
 * Christopher Nolan's brother Jonathan is sometimes his screenwriting partner.
 * The Bryan brothers are a 14-time Grand Slam-winning doubles tennis pair that are known by their creepy ability to be in perfect sync both on and off the court.
 * The Brothers Grimm
 * Oswald Boelcke, German WWI Flying Ace and developer of the Dicta Boelcke, was initially posted to Fliegerabteilung 13 (Aviation Section 13). His bother Wilhelm was also a member of said group. They were such a successful team they aroused antipathy in other members of the section. As a result, Wilhelm was transferred away from his brother.
 * Manfred (the Red Baron) and Lothar von Richthofen. Both served in the same squadron, and were amongst the highest scoring aces of WWI.
 * Andrew and Allen Cunningham in World War II . Andrew in the Royal Navy and Allen in the British Army. Andrew was a genuine Four-Star Badass. Allen was at first thought to be so because of his conquest of Ethiopia from the Italians. But he went down in history as a might-have-been because he lost his nerve facing Erwin Rommel.
 * The Sedin twins, Henrik and Daniel, of the National Hockey League's Vancouver Canucks. They are decent players on their own, but when they're on the ice together, look the fuck out.
 * Before the Sedins, there were the Sutters, six brothers who all played in the NHL. Brent and Duane were teammates on the New York Islanders, while twins Rich and Ron played together for the Philadelphia Flyers and St. Louis Blues.
 * Sandra Bullock, wearing her producer hat, is sometimes partnered with her sister Gesine Bullock-Prado.
 * German director Fatih Akin usually manages to include a part for his brother Cem in his movies.
 * German football legend Uwe Seeler and his brother Dieter frequently played together for the Hamburger SV and a few times in the West German national team. It was said that any player who fouled Uwe in a bad way could expect to be tackled by protective big brother Dieter later in the game.
 * Fritz Walter (captain) and his brother Ottmar were a successful team within the forward line the 1950s team of 1. FC Kaiserslautern and the West German national team that won the 1954 World Cup.
 * Robert F. Kennedy served as attorney-general to his elder brother, President John F. Kennedy.
 * Secretary of State John Foster Dulles and his brother Allen, head of the Central Intelligence Agency, both played important parts in shaping United States policy during the Cold War.
 * Writer Stan Lee (born Stanley Martin Lieber) and his artist brother Larry Lieber have collaborated on many comics, including e. g. the Spider-Man newspaper strip.
 * Charlie Chaplin and his half-brother Sidney; the latter e. g. often played supporting parts in Charlie's movies.
 * The Jackson Five, back in the day.
 * The Nicholas Brothers, tap-dancing legends.
 * Fred and Adele Astaire.
 * King Frederick the Great and his middle brother Henry (Heinrich), commanders of the two main Prussian field armies in the Seven Years' War (and also the War of Bavarian Succession, 1778-1779).
 * General Charles Mann, Lord Brome, Marquess and Earl of Cornwallis (best remembered for being forced to capitulate at Yorktown) and his brother, Admiral William Mann, Earl of Cornwallis.
 * Harold, Gyrth and Leofwine Godwinson at the Battle of Hastings, Gyrth and Leofwine even died together. Harold and Gyrth had formerly teamed up against their other brother Tostig at the Battle of Stamford Bridge, and before Tostig's defection Tostig and Gyrth were a close team.
 * The Farrelly brothers
 * Homestar Runner is made by Mike and Matt Chapman ("The Brothers Chaps").
 * Dwarf Fortress is mostly the work of Tarn Adams, but his brother Zack is helping him.
 * The legends of Western Animation, Max and Dave Fleischer of Fleischer Studios!

Comics

 * The Hulk and She Hulk, cousins.

Literature

 * Sostratos and Menedamos, cousins, in Over the Wine Dark Sea and its sequels. The pair of them are Intrepid Merchants from Rhodes in the Hellenistic Age, and have to deal with nature, pirates, warlords, strange cargo (like peacocks), and, worst of all, each other.
 * Nancy Drew's sidekicks George and Bess are cousins (though unrelated to Nancy herself).
 * Merry and Pippin, cousins, from The Lord of the Rings.
 * Hunter and Sky, cousins, from Cate Tiernan's Sweep series.
 * More than one in A Series of Unfortunate Events, including the main protagonists.
 * Ivan and Miles are cousins and Heterosexual Life Partners in Vorkosigan Saga.

Live Action TV

 * The Dukes of Hazzard, cousins.
 * Kate, Sarah, and Nicholas Redding, the heroes of Pirate Islands.

Western Animation

 * Ben 10 has cousins who certainly act like, and to an extent are treated like, siblings.
 * Though only posing as siblings, Illana and Lance from Sym-Bionic Titan could count as they are not romantically involved, but care strongly with each other.

Real Life

 * Crown Prince Frederick of Prussia and his cousin Prince Frederick Charles commanded two main armies in the wars of 1866 and 1870-1871.