Special Agent Sarah Ashburn and Detective Shannon Mullins - The Heat (2013)
Why We Love Them: Why are buddy cop movies starring women such a rarity? McCarthy and Bullock made the perfect odd couple as two very different cops partnered together for a case.
The chemistry between them is undeniable, and it's impossible to ignore how much fun they're having with their characters.
They say: "We had no interest in making two wacky cops that are bad at their job and are fighting over lipstick in the car," says Melissa McCarthy.
Selina and Jen - The Dark Knight Rises (2012)
Why We Love Them: Jen's appearance in TDKR was fleeting, true, but undoubtedly unforgettable. The hugely under-used Juno Temple worked her magic on the character, giving audiences a tantilising (and very necessary) peek into Selina's background.
We'd love to see more of these two together (and see if those Jen/Holly Robinson comparisons ring true).
They say: "This place is a little dead." "It'll liven up in a minute, trust me."
The Grady Girls - The Shining (1980)
Why We Love Them: Easily the creepiest pairing on our list, The Grady girls hang out in hotel corridors and specialise in terrifying little boys on tricycles.
They say: "Come play with us, Danny."
Joan Jett and Cherie Currie - The Runaways (2010)
Why We Love Them: The first ladies of rock and roll got a cinematic makeover in this biopic. Joan and Cherie were an electrifying duo onstage, and their movie versions were no different, thanks to stellar performances from Kristen Stewart and Dakota Fanning.
They say: "I made it a very early decision that the story was going to be about Cherie and Joan…so that was a conscious effort, you know, to...make it more personal on the two of them and their relationship," said Director Floria Sigismondi.
Anastasia and Drizella - Cinderella (1950)
Why We Love Them: They're lazy, snooty and rude, but they're also deliciously evil.
Sometimes Disney princesses can be just a bit too delightful, and these two stepsisters give the movie a well-needed injection of nasty.
They say: "I'm so eligible!" Anastasia.
Gillian and Sally - Practical Magic (1998)
Why We Love Them: It's Bullock meets Kidman in this tale of occult sisters trying to lift their man-killing family curse.
It's clear the stars had a blast making the movie, and in the scene where the Owens sister overdo the booze wasn't acted at all. You can blame Nicole Kidman for providing the bad tequila...
They say: "Nicole claims that she's the best drinker? You know what? I'd probably have to give that to her," says Sandra Bullock.
Jane and Blanche - What Ever Happened To Baby Jane? (1960)
Why We Love Them: The union of Hollywood's finest Bette Davis and Joan Crawford was always going to be a powerful one, and Robert Aldrich's claustrophobic thriller didn't disappoint.
The actresses put it captivating performances as the hyper competitive Hudson sisters who are torn apart by their obsession with fame.
They say: "When I came across What Ever Happened To Baby Jane? , I sent it to Bob Aldrich and told him it was for Bette and me." Joan Crawford.
Nina and Lily - Black Swan (2010)
Why We Love Them: Because we still don't quite understand them.
Director Aronofsky drew inspiration from Fyodor Dostoyevsky's The Double when casting his psychological ballet thriller, and stars Portman and Kunis cleverly blur the lines between their vastly different (but often all-too-similar) characters.
They say: "However [Portman] would do it, I would do it the opposite." Mila Kunis.
Donna and Sophie - Mamma Mia! (2008)
Why We Love Them: Coming across more like mates than mother and daughter, Meryl Streep and Amanda Seyfriend dance, sing and cavort to their hearts content in Phyllida Lloyd's ABBA-fest.
The whole movie is a journey of discovery for the pair, and it's refreshing to see such a healthy, open family relationship onscreen.
They say: “You raise your game when you are working with somebody that gifted." Amanda Seyfried on Streep.
Margo and Eve - All About Eve (1950)
Why We Love Them: These duos aren't all loved-up besties, you know.
Both Joan Crawford and Anne Baxter put in legendary performances as the aging Broadway star and her usurper respectively, and rather than loving them for their friendship, we love them for their devastating rivalry.
They say: "Nice speech, Eve. But I wouldn't worry too much about your heart. You can always put that award where your heart ought to be." Margo Channing.